89 results on '"density functional theory"'
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2. Selenyum Katkılı Çinko Oksit'in Yapısal ve Elektronik Özelliklerinin Teorik İncelenmesi.
- Author
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ÇELİK, Veysel
- Subjects
- *
CONDUCTION electrons , *ERROR analysis in mathematics , *SOLAR cells , *DENSITY functional theory , *ELECTRONIC structure , *ATOMS - Abstract
Due to its electronic properties, Zinc Oxide (ZnO) is one of the important materials used in new generation solar cells. However, it is necessary to increase the working efficiency of pure ZnO with the rays coming from the sun. Doping with foreign atoms is one of the important techniques in this sense. In this study, the doping of ZnO crystal with Se atom was investigated theoretically. Density functional theory (DFT) was used in the calculations. However, DFT+U correction was made in the calculations to correct the known errors of the theory. With this method, the band gap of pure ZnO was calculated at 3.27 eV. This value is close to the experimental value of 3.44 eV. The Se atom causes local distortions in the crystal structure. However, these deteriorations do not significantly change the characteristic properties of the ZnO crystal. Doping with Se mainly leads to a change in the electronic structure. When the Se and Zn atoms, which have more valence electrons, are replaced, two occupied energy levels are formed in the band gap, above the valence band maximum, due to impurity. These energy levels increase the light absorption activity of ZnO in the visible region. Another important data obtained is that the lack of oxygen in the Se-doped ZnO crystal positively affects the absorption activity in the visible region. [ABSTRACT FROM AUTHOR]
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- 2023
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3. The First-Principles Study On The Investigation of Magnetic and Electronic Properties of Ga4X3Mn (X = P and As)
- Author
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Aytaç Erkişi
- Subjects
semiconductor ,antiferromagnetism ,ab initio calculations ,density functional theory ,yarı-iletken ,antiferromanyetizma ,ab initio hesaplamaları ,youğunluk fonksiyonel teorisi ,Science (General) ,Q1-390 - Abstract
In this study, the magnetic nature and also, electronic characteristics of Ga4X3Mn (X=P and As) systems, which have simple cubic structure confirming P4 ̅3m space group and 215 space number, have been reported. All calculations realized within the framework of ab initio simulation methods have been performed using the meta-generalized gradient (META-GGA) approach within the Density Functional Theory (DFT). In view of the energy-volume curves and the calculated cohesive and formation energies for considering four different types of magnetic orders, it has been detected that these compounds have A-type antiferromagnetic nature. Also, the examined electronic behaviors in the A-type antiferromagnetic order of the related systems show that all two compounds are semiconductors due to having small band gaps in their electronic band structures (Eg = 0.23 eV for Ga4P3Mn and Eg = 0.16 eV for Ga4As3Mn).
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- 2022
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4. Employing of 2-Acetylpyridine Based Chalcone as Hg2+ Sensing Material: Experimental and Theoretical Examination
- Author
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Alparslan Atahan, Mustafa Zengin, Mecit Aksu, and Ahmad Badreddin Musatat
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chalcone ,sensors ,uv/vis spectroscopy ,density functional theory ,kalkon ,sensörler ,uv/vis spektroskopisi ,yoğunluk fonksiyon teorisi ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Science ,Science (General) ,Q1-390 - Abstract
This study reports the evaluation of 2-acetylpyridine based chalcone structure as a useful sensing material for Hg2+ ion detection by the means of UV-visible spectroscopy. In this context, firstly, the most common twenty metal ions were treated by the chalcone structure which was synthesized from 2-acetylpyridine and 4-diphenylaminobenzaldehyde according to the known procedures. As result, the studied chalcone compound exhibited good sensing activity towards Hg2+ ion in acetonitrile/water medium with significant red-shift phenomenon. In addition, some photophysical/electronic parameters of the chalcone and its Hg2+ complex were determined experimentally and theoretically. B3LYP, PBE0 methods and SVP, TVZP, and TVZPP basis sets were used for theoretical calculations in acetonitrile media. Finally, experimental results were explained and the proposed sensing mechanism was supported via density functional theory (DFT) outputs.
- Published
- 2022
5. 2-(2-Bromo-5-Florofenil)-7-Metoksi-3-Nitro-2H-TiyokromenMolekülünün Kimyasal Aktivitesi, Hirshfeld Yüzey Analizi ve Moleküler Kenetleme Çalışmaları.
- Author
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BAYRAKDAR, Alpaslan
- Subjects
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MOLECULAR orbitals , *DENSITY functional theory , *BINDING energy , *DRUG design , *SURFACE analysis , *MOLECULAR docking , *INTERMOLECULAR interactions - Abstract
In this article, the structural and electronic properties of 2-(2-Bromo-5-Fluorophenyl)-7-Methoxy-3-Nitro-2H-Thiochromene were investigated theoretically using density functional theory. Molecular orbital analysis HOMO-LUMO was used to investigate the stability of the molecule. Intramolecular and intermolecular interactions in the crystal structure of the title compound were visualized by hirshfeld surface analysis and examined. Lipinski's rule of five showed that the 2-(2-Bromo-5-Fluorophenyl)-7-Methoxy-3-Nitro-2H-Thiochromene molecule is an orally active candidate and may be suitable for new drug design. In the last part of the study, the best binding pose of 4RJ3 PDB encoded protein to the ligand (the molecule under study) was determined by molecular docking method, and the binding energy and binding mechanism were examined. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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6. 4-(5-metil-[1, 2, 4] triazolo [1, 5-a] pirimidin-7-iloksi) ftalonitrilin Yapısal ve Spektral Özellikleri: TD-DFT Yöntemi ile Analizi, ADME analizi ve Moleküler Doking Simülasyonları.
- Author
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ALTUN, Kenan, YILDIKO, Ümit, TANRIVERDİ, Aslıhan Aycan, TEKEŞ, Ahmet Turan, ATA, Ahmet Çağrı, KARTAL, Barış, and ÇAKMAK, İsmail
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DENSITY functional theory , *DOSAGE forms of drugs , *BENZENEDICARBONITRILE , *ENERGY bands , *BAND gaps - Abstract
In this study, 4-(5-methyl-[1,2,4]triazolo[1,5-a]pyrimidine-7-yloxy) phthalonitrile (coded as MTPPN) was chosen as the phthalonitrile compound and the quantum chemical and in-silico studies have been done. First, the basis set of the time dependent density functional theory (TD-DFT) method was used and the boundary orbital energies and band gap calculations of the molecule were performed. Analysis of atoms in molecules (AIM) theoretical calculations is presented to learn about electron density and bond critical point. In addition, absorption, distribution, metabolism, and excretion analyzes (ADME) were performed for the drug potential of the compound. On some enzymes effect of MTPPN compound was examined. The docking score was obtained for AChE, BChE, α-GLY proteins -7.864, -6.848, and -5.511 kcal/mol, respectively. MTPPN gave a good inhibitory performance in an in-silico study as a drug candidate. [ABSTRACT FROM AUTHOR]
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- 2022
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7. A Theoretical Study on Electronic Behavior and Mechanical Properties of Ferromagnetic Manganese Selenide: AgMn2Se4
- Author
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Aytaç Erkişi and Gokhan Surucu
- Subjects
half-metallic ,ferromagnet ,density functional theory ,chalcogenide ,mechanical properties ,Science (General) ,Q1-390 - Abstract
In this study, the electronic behavior and mechanical properties of the ferromagnetic chalcospinel manganese-based selenide (AgMn2Se4) which crystallized in face centered cubic structure with space group Fd3 ̅m and space number 227, were investigated. All ab initio calculations were carried out by Generalized Gradient Approximation (GGA) under spin polarization. For this composition, three different type magnetic orders were considered to detect the most stable magnetic character. For the given composition, the results of the computations indicate its ferromagnetic nature since this compound has a lower ground state energy in this magnetic order than in other magnetic phases. After determining the most energetically stable magnetic phase, the electronic behavior in this magnetic arrangement was examined. The observed electronic band structure under spin polarization of this compound shows that this selenide system is almost half-metallic material due to having small band gap (Eg = 0.09 eV) in the minority spin state. In addition, the mechanical stability was determined with the help of elastic constants which were also employed to determine the mechanical characteristics of this compound.
- Published
- 2021
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8. XA yapıdaki Ti2RuSn ters-Heusler alaşımının yapısal, elektronik, elastik ve termodinamik özelliklerinin teorik olarak incelenmesi.
- Author
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ALBAYRAK, Erol
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ELASTIC constants , *ELECTRONIC band structure , *TERNARY alloys , *SPINTRONICS , *ELASTICITY , *DENSITY functional theory , *ALLOYS - Abstract
Structural, magnetic, electronic and elastic properties of the ternary Ti2RuSn alloy in reverse- Heusler (XA) structure were investigated using density functional theory and generalized grandyent approach. It was seen that the calculated optimized lattice constant, total magnetic moment and electronic band structure were compatible with the available data in the literature. From the spin polarized band calculation, it was predicted that the Ti2RuSn alloy has a band gap of 0.405 eV in the spin-down orientation, while it shows metallic properties in the spin-up orientation and therefore has a semi-metallic ferromagnetic nature. The results of the second order elastic constants were found to meet the Born mechanical stability criteria for this alloy and to be mechanically stable. In addition, it was determined that this alloy, which has a B/G ratio of 3.23 according to Pugh criteria, has a ductile nature due to its greater than 1.75 limit and exhibits anisotropic behavior due to its anisotropy factor (A) of 2.88. It can be said that the investigated alloy is a promising candidate for spin electronics applications. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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9. Detonation Parameters of the Pentaerythritol Tetranitrate and Some Structures Descriptors in Different Solvents - Computational Study
- Author
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Cihat Hilal, Mehmet Erman Mert, and Müşerref Önal
- Subjects
petn ,density functional theory ,organic solvents ,yoğunluk fonksiyonu teorisi ,organik çözücüler ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Science ,Science (General) ,Q1-390 - Abstract
Pentaerythritol tetranitrate (PETN, C5H8N4O12) is a relatively stable explosive nitrate ester molecule. It has been widely used in various military and public industrial productions. In this study, the solubility tendency of PETN in different organic solvents was investigated theoretically. Several physicochemical parameters of PETN such as density, detonation pressure, temperature, rate and products of detonation reaction were investigated using the B3LYP functional and basic set of polarization functions (d, p) containing 6-31G**. The obtained results have been compared with the literature values. Furthermore, the stability and reactivity of PETN in acetone, diethyl ether, ethanol, tetrahydrofuran, toluene and methylene chloride were examined. Results revealed toluene is a good solvent to increase the explosive properties of PETN.
- Published
- 2021
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10. Ab-initio Calculations; Mechanical and Electronic Properties of New M4As3Co (M: Al, Ga) Compounds
- Author
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Buğra Yıldız and Aytaç Erkişi
- Subjects
semiconductor ,zero band gap ,density functional theory ,ferromagnet ,Science (General) ,Q1-390 - Abstract
In this study, electronic, magnetic and mechanical properties of Al4As3Co and Ga4As3Co compounds have been investigated in detail. All the calculations have been done by using Vienna Ab initio Simulation Package by using Generalized Gradient Approximation (GGA) within Density Functional Theory (DFT). M4As3Co (M: Al, Ga) compounds have simple cubic structure and they have F-43m space group with 216 space number. In order to find most suitable magnetic order, ferromagnetic and three type of antiferromagnetic orders have been employed. Although all the ground state energies for both of our materials are close to each other, it is understood that, energetically most stable magnetic order is ferromagnetic order. After optimization procedure, electronic band structures with density of states have been plotted. Plots prove that, Al4As3Co compound has semiconductor nature with very little direct band gap 0.044 eV while Ga4As3Co compound has zero indirect band gap. Finally, elastic constants have been calculated and important mechanical properties have been estimated. As result of these estimation, it could be said that our materials are mechanically stable.
- Published
- 2021
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11. 2-kloro-1-(6-floro-3,4-dihidro-2H-kromen-2yl)ethanon Yapısının Yoğunluk Fonksiyonel Kuramı İle Kimyasal Aktivite HesaplamalarıZeynep DEMİRCİOĞLU1*, Serap UZUN2.
- Author
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DEMİRCİOĞLU, Zeynep and UZUN, Serap
- Subjects
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MOLECULAR shapes , *MOLECULAR interactions , *DENSITY functional theory , *ELECTRIC potential , *SURFACE analysis , *FRONTIER orbitals - Abstract
In this study, the 2-chloro-1-(6-flouro-3,4-dihydro-2H-chromen-2yl)ethanone molecule which was synthesized and whose structure was illuminated by X-ray diffraction method in previously study was determined by chemical activity, second order nonlinear optical properties and interactions with DNA bases were investigated. Density functional theory was chosen as the theoretical method because of it is significant values close to experimental and its computational cost. There is no imaginary frequencies was observed as a result of the frequency calculations also supported the optimized structure and thus other properties were obtained and interpreted from the optimized structure. The stable molecular geometry of the studied molecule was obtained by optimization. DFT/B3LYP/6-311++G(d,p) bases set was used in all theoretical calculations. It was seen that the geometric parameter values of the optimized molecule were compatible with the experimental data and thus other properties obtained through the optimized structure were calculated and interpreted. In the calculation of the chemical activity of the molecule, hardness, softness and other chemical activity parameters were obtained by frontier molecular orbital (HOMO, LUMO) energies. Molecular electrostatic potential (MEP), charge population and Fukui functional analaysis was determined in which regions the structure is susceptible to chemical interactions. Inaddition to these, molecular interactions, Hirshfeld surface maps, interaction percentages of atoms with each other (2D-finger print) were examined by Hirshfeld surface analysis. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
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12. First-Principles Study on Magnetic Nature and Electronic Behavior of Silver-Based Sulfide: Ag3MnS4
- Author
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Aytaç Erkişi and Gokhan Surucu
- Subjects
semiconductor ,antiferromagnet ,ferromagnet ,density functional theory ,chalcogenide ,Science (General) ,Q1-390 - Abstract
This investigation is about the electronic and magnetic character of the ternary silver-based sulfide (Ag3MnS4) crystallized in sulvanite type crystal structure with space group P4 ̅3m and space number 215. The mentioned characteristics has been examined by Generalized Gradient Approximation (GGA) with spin effect under Density Functional Theory (DFT). Four different magnetic phases have been considered to investigate the proper magnetic order for this system. As a result of calculations, it has been understood that, for Ag3MnS4 compound, the energetically most favored magnetic order is A-type antiferromagnetic. After the well-optimized structural parameters and relaxed atomic positions in its suitable magnetic order have been obtained, the electronic characteristic of this antiferromagnet system indicating semiconducting behavior due to the observed a small direct band gap (Eg = 0.325 eV) in both spin states, has been investigated. Also, this compound has thermodynamic stability and structural synthesizability due to its calculated negative formation energy values for all different type magnetic phases.
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- 2020
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13. Novel Heterocyclic Azo Compounds: Synthesis, Characterization and DFT Calculations
- Author
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Tahir Tilki, Barış Sezgin, and Shahodat Irmumınova
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azo compounds ,heterocyclic ,density functional theory ,Science (General) ,Q1-390 - Abstract
Today, it is of great importance to synthesize new azo compounds as well as to conduct research in different areas of use. More than one usage area is increasing day by day in high-tech products (laser printing materials, printer toners, liquid crystals, etc.) as well as in many sectors such as paper, food, cosmetics, textile and leather. In this study, considering these advantages, the compounds of 3-amino-1H-pyrazol-5-ol, 1H-1,2,4-triazol-3-amine, 3-amino-1H-phenyl-5-ol were used as starting materials. As a result of azo coupling of diazonium salts with resorcinol and 3,5-dihydroxy benzoic acid, new azo compounds were synthesized, their structures were characterized by spectroscopic methods such as FT-IR and 1H-NMR, and different solvent effects on visible absorption spectra were investigated. Molecular geometry and vibration frequency calculations of synthesized compounds were made with Density Functional Theory (DFT) using 6-311G (d,p) basis set and B3LYP level. Additional, electronic properties and HOMO-LUMO orbital calculations were carried out with time dependent DFT (TD-DFT) approach. As a result of this study, it has been observed that azo compounds containing heterocyclic amine groups have batchromic effects and bright colors. It is anticipated that this study will make important contributions to the literature and the dyestuff industry and will form a basis for potential applications.
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- 2020
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14. Fenazin Tabanlı Bileşiklerin OLED ve TADF Özelliklerinin İncelenmesi.
- Author
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TURHAN, Zeynep Şilan
- Subjects
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DELAYED fluorescence , *DENSITY functional theory , *BAND gaps , *PHENAZINE , *FUNCTIONALS - Abstract
In this study, dibenzo[a,c]phenazine based acceptor was combined with donors and acceptor to obtain donor-π-acceptor type potential thermally activated delayed fluorescence (TADF) emitters. All molecules’ structural and electronic properties were computed theoretically at the level of Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TD-DFT) with the application of three different hybrid functionals. Most of the designed structures were found to have the potential to be TADF compounds. This is because it has a very narrow energy gap between the first excited single and triple states. As a result, the designed derivatives can be calculated as the best candidates for the purpose and also have very strong potential to serve as an efficient Organic Light (Emitting Diode) OLED material [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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15. Co-M-Ni (M= Fe, Ag) Geçiş Metali Nanoalaşımlarının Yapısal, Enerjik ve Manyetik Özellikleri.
- Author
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YILDIRIM, Hüseyin
- Published
- 2021
- Full Text
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16. Theoretical Study of CCl3 Adsorption on C20 Fullerene
- Author
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Ferhat DEMİRAY
- Subjects
density functional theory ,c20 fullerene ,ccl3 ,molecular structures ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Science ,Science (General) ,Q1-390 - Abstract
In this study, structural and electronic properties of CCl3 (carbon trichloride) doped fullerene (C20CCl3) were obtained by using Density Functional Theory. In this calculations, adsorption energy was obtained as -4.17 eV and -3.41eV for LDA and GGA, respectively. In optimized C20CC13 structure, bond lengths between C - Cl atoms increased with respect to bond lengths in CC13 molecular structure. It has been calculated that the bond lengths between the carbon atom which the CCl3 molecule is attached in the fullerene and the other carbon atoms which it is bonded are also increased. GapHL values in the molecular structure obtained by combining CCl3 and fullerene were obtained as 0.57 and 0.73 eV for LDA and GGA, respectively. The C20CCl3 molecule can be evaluated as a semiconductor material for both LDA and GGA approach according to GapHL values.
- Published
- 2020
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17. Potansiyel Korozyon İnhibitörü Olarak Pirimidin Türevlerinin DFT Hesaplaması ile Teorik Çalışmalar.
- Author
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ERGAN, Erdem
- Subjects
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FRONTIER orbitals , *MOLECULAR orbitals , *DENSITY functional theory , *ELECTRIC potential , *CORROSION prevention , *ELECTRONEGATIVITY - Abstract
In this work, the corrosion prevention behaviors of pyrimidine derivatives (1-12) were investigated by theoretical quantum chemical calculation. Quantum chemical parameters obtained by theoretical calculations such as the Highest Occupied Molecular Orbital (HOMO), Lowest Empty Molecular Orbital (LUMO), molecular electrostatic potential maps (MEP), electronegativity (χ), chemical potential (µ), global electrophilicity index (ω), chemical hardness (η) and global softness (σ) for all compounds were studied using density functional theory (DFT) at the B3LYP / 6-31G (d, p) level. Also, the fraction of transferred electrons (ΔN) between the iron surface and the pyrimidine derivatives compounds were calculated. However, nonlinear optical (NLO) properties have also been investigated. When the quantum chemical parameters obtained by theoretical calculations are examined, it has shown that compound 10 can be used as a good corrosion inhibitor with small ΔEgap (EHOMO-ELUMO), chemical hardness (η) values and high global electrophilicity index (ω), "ΔN" values. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
18. Cu ve Fe Metalleri için tiyadiazol türevi bileşiklerin kuantum kimyasal hesaplamaları ve korozyon inhibisyon aktiviteleri.
- Author
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KARAKURT, Tuncay
- Subjects
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CHARGE exchange , *IONIZATION energy , *CHARGE transfer , *CHEMICAL potential , *DENSITY functional theory , *ELECTRONEGATIVITY , *ELECTRON affinity , *FUNCTIONAL groups - Abstract
In this study, theoretical computational studies were carried out to investigate the corrosion inhibition effect of Thiadiazole derivative compounds on Cu and Fe metal atoms. Molecular modeling of all compounds was used with Gaussian 09 program, DFT/B3LYP theorem and 6-311G (d) base set. Inhibition activities of the compounds which are inhibitor candidate for Fe and Cu metals were observed in the order L3> L1> L4> L2. It has been found that the inhibitory effect of the Thiadiazole derivative compounds depends on the electronic nature of the functional groups present in these compounds. Quantum chemical parameters of all compounds; HOMO and LUMO orbital energies, some quantum chemical parameters; electron affinity (EA), ionization potential (IP), electronegativity (χ), global hardness (η), global softness (S) and chemical potential (µ) values were calculated. Using these parameters, the electron transfers fraction (N) of all compounds expressing the charge transfer from the inhibitor to the metal was calculated. Finally, the calculated anti-corrosion effects of the compounds were compared with each other. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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19. Halojen Atomları ve Siyano Grubunun Hekzasen Molekülünün Optik, Elektronik ve Yük Transfer Özellikleri Üzerine Etkisinin İncelenmesi: Moleküler Dizayn Yöntemi, Yapı-Özellik İlişkisi.
- Author
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YAKALI, Gül
- Subjects
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TIME-dependent density functional theory , *MOLECULAR shapes , *MATERIALS science , *REORGANIZATION energy , *CHARGE transfer - Abstract
In this study, the π-conjugated hexacene molecule was designed with different halogen atoms (Fluorine, Chlorine, Bromine), differently positioned cyano groups and its electronic, optical and charge transfer properties were investigated by time-dependent and time-independent Density Functional Theory (DFT). The substituent effect on the molecular geometry, reorganization energy, frontier orbitals, ionization potential (IP) and bond length alternation (BLA) depending on nötr and charged states, electronic affinity (EA) of the five molecules were investigated to establish the relationship between structures and properties .To gain a better understanding of the substituent effect on the charge transport property, the results of designed molecules were compared with hexacene and antracene molecules. The electron injection barrier of the new designed molecules is lower than hexacene molecule and have more effective hole charge transfer property which is comparable to that of antracene known as a good hole charge carrier. I belived that, new designed hexacene derivatives may be used as optoelectronic devices which could attract great attention in material sciences. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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20. Bis[2-(metilamino)troponato]bakır(II) Molekülünün Yapısal ve Elektronik Özelliklerinin Deneysel ve Kuramsal Analizleri.
- Author
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UZUN, Serap and DEMİRCİOĞLU, Zeynep
- Subjects
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DENSITY functionals , *COMPUTATIONAL chemistry , *DENSITY functional theory , *OPTICAL materials , *CHEMICAL structure , *INTROGRESSION (Genetics) - Abstract
The molecular, electronic and chemical structure of the Bis[2-(methylamino)troponato]copper(II) molecule was clarified. It is aimed to determine the local and global chemical activity parameters and electrophilic and nucleophilic nature by computational chemistry method of density functional theory of the molecule which can not be obtained experimentally. In addition, the tendency of the studied molecule to be an optical material has been investigated. Stabilization energy of the structure, conjugate interactions, stabilization of orbital orbitals, hybridization percentages and transition states were examined by natural bond orbital analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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21. A density functional theory study on the linear and nonlinear optical behavior of single fluoreatoom doped lithium plugs
- Author
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Güvenir, Selçuk, Ünal, Arslan, and Güvenir, Selçuk
- Subjects
Optik Özellikler ,Flor ,Lump ,Lityum ,DFT ( Density Functional Theory) ,Fluorine ,Lithium ,Yoğunluk Fonksiyonel Teorisi ,DFT ,YFT (Yoğunluk Fonksiyonel Teorisi) ,Topak ,YFT ,Optical Properties ,Density Functional Theory - Abstract
Tek halojen atomu doplamalı lityum topakların lityum bazlı pil, optik sensör, iletişim ve veri depolama sistemlerinde kullanılabilmesi için optik özelliklerin potansiyel uygulamalar ve malzemelere uygulanmalarının artması amaçlanmıştır. Çizgisel LinF (n=1-8) topaklar ve çizgisel olmayan LinF (n=2-8) topakların en kararlı yapılarının optik davranışlarını ortaya çıkarmaktır. Bu çalışmada; tek flor atom doplamalı lityum topaklarının çizgisel (LinF, n=1-8) kararlı yapıları ile çizgisel olmayan (LinF, n=2-8) kararlı yapılarda ki optik özelliklerini, hibrit-yoğunluk fonksiyonel teorisi (h-YFT) yardımıyla kuramsal olarak araştırılmıştır. It is aimed to increase the application of optical properties to potential applications and materials so that single halogen atom doped lithium pellets can be used in lithium-based batteries, optical sensors, communication and data storage systems. The aim is to reveal the optical behavior of the most stable structures of linear LinF (n=1-8) pellets and nonlinear LinF (n=2-8) pellets. In this study; the optical properties of linear (LinF, n=1-8) stable structures and non-linear (LinF, n=2-8) stable structures of single fluorine atom-doped lithium pellets were investigated theoretically with the help of hybrid-Density Functional Theory (h-DFT).
- Published
- 2023
22. BaRu2As2 Malzemesinin Fiziksel Özelliklerinin Yoğunluk Fonksiyonel Teorisi Kullanılarak İncelenmesi.
- Author
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KARACA, Ertuğrul
- Abstract
Ab initio pseudopotential calculations have been made to investigate structural, electronic, vibrational, and superconducting properties of BaRu2As2. Electronic results show that the calculated density of states at the Fermi level (N(EF)) is 1.79 states/eV and N(EF) is mainly contributed by Ru 4d states and As 4p states. A linear response approach is used to determine phonon dispersion curves and phonon density of states for this compound. The phonon dispersion curves and phonon density of states indicate the optimized structure of BaRu2As2 is dynamically stable. Furthermore, the linear response method and theMigdal-Eliashberg approach have been used to calculate electron-phonon matrix elements for BaRu2As2. By using these matrix elements, the average electron-phonon coupling parameter is found to be weak strength such as λ=0.21. This result confirms that very small electron-phonon interaction occurring in this compound. This low value of (λ) explains the absence of conventional superconductivity up to 0.1 K in this compound. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
23. [Ni(2-Benzimidazol-il-üre)2(etanol)2][NO2]2 Bileşiğinin Yoğunluk Fonksiyoneli Teorisi Kullanılarak Yapılan Bazı Kuantum Kimyasal Hesaplamaları.
- Author
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TURHANİRAK, Zeynep and POYRAZ, Mehmet
- Subjects
- *
FRONTIER orbitals , *DENSITY functional theory , *ELECTRIC potential , *MOLECULAR structure , *DIPOLE moments - Abstract
The theoretical calculations of the [Ni(2-Benzimidazoly-urea)2(ethanol)2] [NO3]2 compound, whose molecular structure was determined with a single crystal X-ray diffraction method, was conducted. Many properties such as optimized geometry and dipole moment obtained in theoretical calculations showed very approximate to experimental values. Apart from these, the frontier orbitals of the compound in the gas phase, the electronic structure parameters from the energies of the calculated frontier orbitals, molecular electrostatic potential map, non-linear optical properties were calculated and interpreted. It is thought that the study will shed light on the molecular property of many organometal complexes. The Density Functional Theory (DFT) was selected as a computational method using the Gaussian 09W program, and the optimized gase phase quantum mechanical data for the complex was obtained in the B3LYP/LANL2DZ level with gen keyword. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
24. (E)-2-((Fenilimino)metil) Fenol Molekülünün Teorik Olarak İncelenmesi.
- Author
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ÖZTÜRK, Erhan, TURHAN IRAK, Zeynep, and GÜMÜŞ, Selçuk
- Abstract
In this work, quantum chemical calculations were computed in the base state using Density Functional Theory at the level of B3LYP/6-31++G(d,p) to obtain information about the 3D geometry and electronic structure of the (E)-2- ((phenylimino)methyl)phenol molecule. Conformations were found by scanning the total energy by rotating around the single bond of the optimized molecular structure. Three-dimensional electrostatic potential maps of the most and least stable conformation were deduced. These conformational structures have calculated the highest filled molecular orbital (HOMO), lowest empty molecular orbitals (LUMO) energies, electronic and molecular properties. In addition, nonlinear optical properties (NLO) were investigated. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
25. An FT-IR and DFT Study of Solvent Effects on Molecular Parameters and Vibrational Frequencies of 3,5-diamino-1,2,4-triazole.
- Author
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BİLKAN, Mustafa Tuğfan
- Abstract
In this paper, solvent environments effects on structural and spectroscopic properties of 3,5-diamino-1,2,4-triazole (Guanazole) antitumor agent have been investigated. Optimized molecular structures were obtained in solvent media. Conformational structures of Guanazole in the gas phase were investigated and the relative population distributions of the conformations were obtained using the Boltzmann distribution. Moreover, the experimental FT-IR spectrum of Guanazole were recorded. In addition, vibrational frequencies and its intensities were calculated for each environment by using of optimized structures and they compared with the experimental data. Density Functional Theory and 6311++G (d,p) basis set were used in the theoretical calculations. Based on the solid phase IR spectrum of pure Guanazole, it was seen that Guanazole is dimeric structure in solid phase. For this reason, the dimer structure of Guanazole has been investigated in detail. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
26. Lityum bor karbür (LiBC) bileşiğinin yapısal, elektronik ve mekanik özelliklerinin basınç altında değişimi.
- Author
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Aydın, Sezgin
- Abstract
The structural, electronic, mechanical and dynamic properties of lithium boron carbide (LiBC) under hydrostatic pressure have been investigated by performing first-principles plane wave density functional theory calculations. It is shown from calculated lattice parameters, c lattice parameter is more sensitive to pressure than a lattice parameter. Furthermore, deviations of the single-crystal elastic constants and related mechanical properties such as bulk, shear and Young's moduli with pressure are studied. It is appeared from detailed density of states and band structures that how does energy gap change with pressure. Combining the results of Mulliken bond population and atomic charge analysis with information acquired from partial density of states curves, binding nature of the crystal is investigated in detail. Furthermore, it is studied how to change length of interlayer and intralayer bonds versus pressure. And, calculated results are compared with experimental and other theoretical data. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
27. Bizmut adsorbe eden çinko oksit nanotellerin manyetik işlevselleşmesi [TR].
- Author
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Kılıc, Sumeyra Guler and Aras, Mehmet
- Abstract
The adsorption of bismuth atom on the surface of zinc oxide nanowires is investigated by carrying out density-functional calculations with Hubbard U correction. Geometry optimizations are performed for a number of adatom configurations, and the adsorption energies and magnetic moments are calculated. The lowest-energy adatom configuration is thus determined. It is found that this configuration possess a canted magnetic moment. This means that the orientation of the magnetic moment vector can be controlled by applying an external magnetic field. Band structure calculations reveal that the existence of this intrinsic magnetic moment causes a exchange splitting of the lower conduction band states. These findings show that the adsorption of bismuth leads to magnetic functionalization of zinc oxide nanowires. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
28. Ru2FeGa Heusler alaşımının yapısal, elektronik, elastik ve fonon özelliklerinin ilk prensip çalışması.
- Author
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Candan, Abdullah
- Abstract
Heusler type alloys are ferromagnetic and are the ideal material for spin-electronic and magneto-electronic applications due to their interesting magnetic properties. The structural, electronic, elastic and phonon properties of the Ru2FeGa Heusler alloy in L21 crystal structure have been analyzed handling density functional theory (DFT) in the Generalized Gradient Approximation (GGA) method. The calculated lattice constant and magnetic moment of Ru2FeGa alloy is in good agreement with theoretical result. The analysis of the band structure reveal that Ru2FeGa is metallic. Furthermore we also calculated the Bulk modulu (B), Shear modulu (G), B/G ratio, Young modulu (E) and unique-crystal elastic constants (Cij) for this alloy. Phonon-dispersion curve has been obtained using the first principle linear-response touch of the densityfunctional perturbation theory. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
29. Theoretical investigation of the structural, electronic, elastic and thermodynamic properties of Ti2RuSn reverse-Heusler alloy in XA structure
- Author
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ALBAYRAK, Erol
- Subjects
Yoğunluk fonksiyonel teori ,elastik özellikler ,ters-Heusler ,yarı metalik malzemeler ,Fizik, Uygulamalı ,Density functional theory ,elastic properties ,inverse-Heusler ,semi-metallic materials ,Physics, Applied - Abstract
Ters-Heusler (XA) yapıdaki üçlü Ti2RuSn alaşımının bazı yapısal özellikleri, manyetikliği, elektronik yapısı ve ayrıca elastisitesi DFT olarak bilinen yoğunluk fonksiyonel teorisi içerisinde yer alan genelleştirilmiş grandyent kabulleri kullanılarak incelenmiştir. Hesaplanan optimize edilmiş örgü sabitinin, toplam manyetik momentin ve elektronik bant yapısının literatürde yer alan mevcut verilerle uyumlu olduğugörüldü. Spin polarize bant hesaplamasından, Ti2RuSn alaşımı spin-aşağı yöneliminde 0.405 eV'luk bir yasak enerji aralığına sahipken, spin-yukarı yöneliminde metalik özellik göstermekte olduğu ve bundan dolayı yarı metalik ferromanyetik bir doğaya sahip olduğu tahmin edildi. İkinci dereceden elastik sabitlerinin sonuçlarının, bu alaşım için Born mekanik kararlılık kriterlerini karşıladığı ve mekanik olarak kararlı olduğu anlaşıldı. Ayrıca, Pugh kriterlerine göre B/G oranı 3.23 olan bu alaşımın 1.75 sınırından büyük olması nedeniyle sünek bir doğaya sahip olduğu ve anizotropi faktörü (A) 2.88 olması nedeniyle anizotropik davranış gösterdiği tespit edildi. İncelenen bu alaşımın spin elektroniği uygulamaları için umut verici bir aday olduğu söylenebilir., Structural, magnetic, electronic and elastic properties of the ternary Ti2RuSn alloy in reverseHeusler (XA) structure were investigated using density functional theory and generalized grandyentapproach. It was seen that the calculated optimized lattice constant, total magnetic moment and electronic band structure were compatible with the available data in the literature. From the spin polarized band calculation, it was predicted that the Ti2RuSn alloy has a band gap of 0.405 eV in the spin-down orientation, while it shows metallic properties in the spin-up orientation and therefore has a semi-metallic ferromagnetic nature. The results of the second order elastic constants were found to meet the Born mechanical stability criteria for this alloy and to be mechanically stable. In addition, it was determined that this alloy, which has a B/G ratio of 3.23 according to Pugh criteria, has a ductile nature due to its greater than 1.75 limit and exhibits anisotropic behavior due to its anisotropy factor (A) of 2.88. It can be said that the investigated alloy is a promising candidate for spin electronics applications.
- Published
- 2022
30. Bazı siklobütan bileşiklerin X-ışını kırınımı ve spektroskopik yöntemler kullanılarak deneysel ve teorik olarak incelenmesi
- Author
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Şimşek, Okan and OMÜ, Lisansüstü Eğitim Enstitüsü, Fizik Ana Bilim Dalı
- Subjects
density ,yoğunluk fonksiyoneli teorisi ,XRD ,Hirshfeld yüzey analizi ,DFT ,NMR ,X-ray diffraction ,FT-IR ,siklobütan ,cyclobutane ,Hirshfeld surface analysis ,YFT ,density functional theory ,X-ışını kırınımı - Abstract
Bu tez çalışmasında; 5-(3-metil-3-fenilsiklobutil)-6H-1,3,4-tiadiazin-2-amin (C14H17N3S) (I), 4,4'-Bis(3-mesitil-3-metilsiklobutil)-2,2'-bitiazol (C34H40N2S2) (II), N-(4-(3-metil-3mesitilsiklobutil)-1H-imidazol-2-yl)asetamid (C19H25N3O) (III) ve 4-((4-(3-metil-3-fenilsiklobutil)tiazol-2-yl)amino)-4-oksobut-2-enoik-asit (C18H18N2O3S) (IV) adlı siklobütan halkası içeren dört adet bileşik incelenmiştir. Sikloalkan bileşiği olan siklobütanlar, tek halkaya sahiptir ve renksizdir. Siklobütanlar, biyoaktif doğal ürünlerde benzersiz bir yapısal özellik sunan dört üyeli karboksillerdir (Hui, et al., 2021). Yalnız başına çok önemli bir özelliğe sahip değil iken; karmaşık türevleri, biyoloji ve biyoteknoloji uygulamalarında çok önemli bir yere sahiptir. Siklobütanların karboksilik asit türevlerinden oluşan bileşiklerin anti-inflamatuar ve antidepresan aktivitelerine ve ayrıca sıvı kristal özelliklerine sahip oldukları bilinmektedir (Dehmlow and Schmidt, 1990). Bu tezde incelenen kristaller, Fırat Üniversitesi Kimya Bölümü Laboratuvarı'nda sentezlenmiş ve kristallerin FT-IR, 1H-NMR ve 13C-NMR spektrumları deneysel olarak elde edilmiştir. X-ışını kırınım verileri ise Ondokuz Mayıs Üniversitesi Fizik Bölümü Kristalografi Laboratuvarı'ndaki STOE IPDS−II difraktometresinden elde edilmiştir. X-ışını kırınım verileri kullanılarak, WinGx paket programları ile kristallerin yapı analizi yapılmıştır. Deneysel verileri desteklemek amacıyla, bileşiklerin X-ışını kırınımından elde edilen moleküler geometrileri Yoğunluk Fonksiyonel Teorisi (YFT) ve B3LYP yöntemi kullanılarak, Gaussian 09W ve GaussView 5.0.9 paket programları ile optimize edilmiş, teorik olarak IR ve NMR spektrumları hesaplanmıştır. Teorik hesaplamalarda baz seti olarak 6-31G (d) ve 6-31G (d, p) kullanılmıştır. Elde edilen teorik değerler ile deneysel değerler karşılaştırılmış ve birbiriyle uyumlu olduğu sonucuna ulaşılmıştır. Ayrıca, CrystalExplorer 17.5 programı ile Hirshfeld yüzey analizi yapılarak moleküller arası etkileşimlerin üç boyutlu görselleri ve molekül içi atomik etkileşimlerin iki boyutlu parmak izi gösterimi oluşturulmuştur. In this thesis study; four compounds containing the cyclobutane ring named 5-(3-methyl-3-phenylcyclobutyl)-6H-1,3,4-thiadiazine-2-amine (C14H17N3S) (I), 4,4'-Bis(3-mesityl-3-methylcyclobutyl)-2,2'-bithiazole (C34H40N2S2) (II), N-(4-(3-methyl-3mesitylcyclobutyl)-1H-imidazol-2-yl)acetamide (C19H25N3O) (III) and 4-((4-(3-methyl-3-phenylcyclobutyl)thiazol-2-yl)amino)-4-oxobut-2-enoicacid (C18H18N2O3S) (IV) were investigated. Cyclobutane, which is a cycloalkane compound, has a single ring and is colorless. Cyclobutans are four-membered carboxyls that present a unique structural feature in bioactive natural products (Hui, et al., 2021). While it does not have a very important feature on its own; complex derivatives have a very important place in biology and biotechnology applications. It is known that compounds consisting of carboxylic acid derivatives of cyclobutane have anti-inflammatory and antidepressant activities as well as liquid crystal properties (Dehmlow and Schmidt, 1990). The crystals examined in this thesis were synthesized in the Laboratory of the Chemistry Department of Fırat University and the FT-IR, 1H-NMR and 13C-NMR spectra of the crystals were obtained experimentally. X-ray diffraction data were obtained from the STOE IPDS−II diffractometer at Ondokuz Mayıs University, Department of Physics, Crystallography Laboratory. By using X-ray diffraction data, the structure analysis of the crystals was done with WinGx package programs. In order to support the experimental data, the molecular geometries of the compounds obtained from X-ray diffraction were optimized with the Gaussian 09W and GaussView 5.0.9 package programs, using the Density Functional Theory (DFT) and B3LYP method, theoretically, IR and NMR spectra were calculated. In the theoretical calculations, 6-31G (d) and 6-31G (d, p) basis sets were used. The theoretical values obtained and the experimental values were compared and it was concluded that they were compatible with each other. In addition, three-dimensional visuals of intermolecular interactions and two-dimensional fingerprint representation of intramolecular atomic interactions were created by performing Hirshfeld surface analysis with the CrystalExplorer 17.5 program.
- Published
- 2022
31. Destek vektör regresyonu yöntemiyle karbon nanotüp benzetim süresinin kısaltılması.
- Author
-
Acı, Mehmet, Avcı, Mutlu, and Acı, Çiğdem
- Subjects
- *
DENSITY functional theory , *CARBON nanotubes , *PREDICTION theory , *SUPPORT vector machines , *NANOTECHNOLOGY - Abstract
Density Functional Theory (DFT) is one of the most important application of Carbon Nanotubes (CNTs). Because of the chemical and physical characteristics of carbon, CNTs play an important role in the field of nanotechnology. The most difficult part of CNT simulations is DFT calculations that take hours or even days. In this study, a Support Vector Regression (SVR) model that reduces the atomic coordinate calculation of CNT simulation duration has been proposed. u, v, and w coordinates which obtained from CNT simulations are predicted with high accuracy using the SVR method within minutes. A dataset containing 10721 samples was created using CASTEP software for the prediction model. The dataset consists of the atomic coordinates and chiral vectors. To evaluate the accuracy of the proposed model, Mean Square Error (MSE), Mean Absolute Error (MAE), Standard Error of the Estimate (SEE) and Correlation Coefficient (R) metrics were used. The dataset is studied separately with and without using 10-fold cross-validation. The results obtained from this study can be used in two ways: 1) The atomic coordinates can be predicted with a low-error without using a simulation program, 2) The estimated results can be used as an initial value of simulation software for reducing duration of the atomic coordinate simulation seriously. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
32. L12 yapıdaki Co3Al ve Co3Ta alaşımlarının mekanik ve dinamik özellikleri.
- Author
-
Örnek, Osman, İyigör, Ahmet, and Arıkan, Nihat
- Subjects
- *
ALLOY analysis , *DENSITY functional theory , *MECHANICAL properties of metals , *INTERMETALLIC compounds , *PHONON dispersion relations - Abstract
The structural, elastic, electronic and vibrational properties of Co3Al and Co3Ta alloys with density functional theory have been investigated. The lattice constants, bulk modulus and its pressure derivative are evaluated and compared with the available data. The numerical first principles calculations of the elastic constants were used to calculate C11, C12 and C44 for Co3Al and Co3Ta alloys. The electronic band structure, electronic total and partial densities of states, and total magnetic moment of the Co3Al and Co3Ta alloys are computed and analyzed in comparison with the existing findings. From the electronic calculations made for both alloys, it was found that the alloys were metallic in nature. Phonon-dispersion curves and their corresponding total and projected densities of states have been obtained for the first time using a linearresponse in the framework of the density functional perturbation theory. The frequencies of the optical phonon modes of both alloys are calculated and found to be 4.46, 6.095 and 10.35 THz for Co3Al, 4.83, 6.11 and 6.86 THz for Co3Ta. Finally, specific heat capacity at a constant volume versus temperature CV of Co3Al and Co3Ta alloys is calculated and discussed using the quasi harmonic approximation. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
33. Paraelektrik ve Ferroelektrik Fazlarda SbSI Kristali Optik Özelliklerinin Araştırılması.
- Author
-
ÖZER, Tahsin and KARATAŞLI, Muhammet
- Published
- 2016
- Full Text
- View/download PDF
34. Epoksiisoindol Türevi bir Bileşiğin Moleküler Modelleme Çalışmaları
- Author
-
Ersin TEMEL and Can ALAŞALVAR
- Subjects
hirshfeld surface ,epoksiisoindol ,yoğunluk fonksiyoneli teorisi ,hirshfeld yüzeyi ,lcsh:TA1-2040 ,lcsh:Q ,lcsh:Engineering (General). Civil engineering (General) ,lcsh:Science ,epoxyisoindole ,density functional theory - Abstract
Bu çalışmada epoksiisoindol türevi olan 2-metil-3a,4,7,7a-tetrahidro-1H-4,7-epoksiisoindol-1,3(2H)-dion bileşiği kuramsal olarak incelenmiştir. Literatürde söz konusu bileşiğin endo ve ekso izomerleri mevcuttur. Bu izomerler başlangıç noktası alınarak moleküller optimize edildi. Optimize yapılar kullanılarak moleküllerin HOMO-LUMO orbitalleri ve elektrostatik potansiyel yüzeyleri (EPS) çizdirildi. İlave olarak moleküllerin paketlenme davranışlarını anlamak için Hirshfeld yüzeyleri ve parmak izi diyagramları çizdirildi. Hesaplamalarda DFT B3LYP/6-311 baz seti kullanıldı.
- Published
- 2018
35. Investigation of structural and spectroscopic properties of newly synthesızed disazo dyes materials by theoretical calculatons
- Author
-
Kızak, Hazal and Taşlı, Pınar Tunay
- Subjects
B3LYP ,Ab-initio ,Azo Dyes ,Gaussian ,Kuantum Kimyasal Hesaplama Yöntemi ,Quantum Chemical Calculations ,Azo Boyarmadde ,Yoğunluk Fonksiyonel Teorisi ,Density Functional Theory - Abstract
Bu tez çalışmasında, A, B, C, D ve E azo boyar moleküllerinin taban seviye denge geometrik yapıları, spektroskopik ve elektronik özellikleri, Yoğunluk Fonksiyonel Teorisi (DFT) tabanlı ab-initio hesaplama yöntemi ve Becke-3-Lee-Yang-Parr (B3LYP) metodu ile 6-31G(d) temel baz seti kullanarak incelenmiştir. İlk olarak sentezlenen moleküller optimizasyon işlemiyle taban denge durumuna getirildi. Kararlı taban denge durumuna gelen moleküllerin yapısal özelliklerini karakterize edebilmek için FT-IR, UV-Vis, 1H-NMR ve 13C-NMR spektroskopik yöntemleri kullanıldı. Daha sonrasında, moleküllerin elektronik yapısını incelemek amacıyla bize moleküler orbital enerjileri hakkında bilgi veren HOMO (En Yüksek Dolu Moleküler Orbital)-LUMO (En Düşük Boş Moleküler Orbital) hesaplamaları gerçekleştirildi. Bu enerjilerden iyonizasyon potansiyeli (I), elektron ilgisi (A), elektronegatifliği (χ), kimyasal sertliği (η) ve kimyasal yumuşaklığı (s) parametreleri hesaplanmıştır. Son olarak yapılan teorik çalışmalar ile deneysel veriler karşılaştırılmıştır. DFT/B3LYP metodu 6-31G(d) baz seti ile gerçekleştirilen hesaplamaların sonuçlarının başarılı olduğu gözlemlendi. Korelasyon grafikleri de sonuçları doğrulamaktadır. In this thesis, the ground state equilibrium geometric structures, spectroscopic and electronic properties of disazo dye molecules A, B, C, D and E are studied via Density Functional Theory (DFT) based on ab-initio method and Becke-3-Lee-Yang-Parr (B3LYP) methods with the basis set of 6-31G (d). Firstly, the synthesized molecules were brought to the base equilibrium state by optimization process. FT-IR, UV-Vis, 1H-NMR and 13C-NMR spectroscopic methods were used to characterize the structural properties of molecules at ground state. After, HOMO (Highest Occupied Molecular Orbital)- LUMO (Lowest Occupied Molecular Orbital) energy levels which give information us about molecular orbital energy are calculated for knowing electronic properties of molecules. Using these energies, ionization potential (I), electron affinity (A), electronegativity (χ), chemical hardness (η) and chemical softness (s) parameters were calculated. Finally, theoretical studies were compared with experimental data. It is observed that the results of the studies which based on DFT/B3LYP calculation methods with the basis set of 6-31G (d) are successful to get the structural, electronic and spectroscopic properties of the molecules considered in this work. Moreover, the correlation plots between the theoretical and experimental data confirm this results.
- Published
- 2021
36. Investigation of some benzotiyazole substitute pirazol-shield and hydrazone derivatives with antiquariative activity potential by the dft method
- Author
-
Aslan, Deniz and Taşlı, Pınar Tunay
- Subjects
Pirazol-Kalkon ,Ab-initio ,Anticancer ,Antikanser ,Benzothiazole ,Pyrazole-Chalcon ,Yoğunluk Fonksiyonel Teorisi ,Benzotiyazol ,Density Functional Theory - Abstract
Bu tez çalışmasında, M1 ve M2 moleküllerinin taban seviye denge geometrik yapıları, spektroskopik ve elektronik özellikleri, Yoğunluk Fonksiyonel Teorisi (DFT) tabanlı ab-initio hesaplama yöntemi ve Becke-3-Lee-Yang-Parr (B3LYP) metodu ile 6-311G(d,p) temel baz seti kullanarak incelenmiştir. İlk olarak sentezlenen moleküller optimizasyon işlemiyle taban denge durumuna getirildi. Kararlı taban denge durumuna gelen moleküllerin yapısal özelliklerini karakterize edebilmek için FT-IR, 1H-NMR ve 13C-NMR spektroskopik yöntemleri kullanıldı. Daha sonrasında, moleküllerin elektronik yapısını incelemek amacıyla bize moleküler orbital enerjileri hakkında bilgi veren HOMO (En Yüksek Dolu Moleküler Orbital)-LUMO (En Düşük Boş Moleküler Orbital) hesaplamaları gerçekleştirildi. Bu enerjilerden iyonizasyon potansiyeli (I), elektron ilgisi (A), elektronegatifliği (χ), kimyasal sertliği (η) ve kimyasal yumuşaklığı (s) parametreler kaydedilmiştir. Son olarak yapılan teorik çalışmalar ile deneysel veriler karşılaştırılmıştır. DFT/B3LYP metodu 6-311G(d,p) baz seti ile gerçekleştirilen hesaplamaların sonuçlarının başarılı olduğu gözlemlendi. Korelasyon grafikleri de sonuçları doğrulamaktadır. In this thesis, the ground state equilibrium geometric structures, spectroscopic and electronic properties of molecules M1 and M2 are studied via Density Functional Theory (DFT) based on ab-initio method and Becke-3-Lee-Yang-Parr (B3LYP) methods with the basis set of 6-311G (d,p). Firstly, the synthesized molecules are brought to the base equilibrium state by optimization process. FT-IR, 1H-NMR and 13C-NMR spectroscopic methods are used to characterize the structural properties of molecules at ground state. After, HOMO (Highest Occupied Molecular Orbital)- LUMO (Lowest Occupied Molecular Orbital) energy levels which give information us about molecular orbital energy are calculated for obtaning electronic properties of molecules. Using these energies, ionization potential (I), electron affinity (A), electronegativity (χ), chemical hardness (η) and chemical softness (s) parameters are calculated. Finally, theoretical studies are compluted with experimental data. It is observed that the results of the studies which based on DFT/B3LYP calculation methods with the basis set of 6-311G (d,p) are successful to get the structural, electronic and spectroscopic properties of the molecules considered in this work. Moreover, the correlation plots between the theoretical and experimental data confirm these results.
- Published
- 2021
37. New Compound of Pyridine-4-Boronic Acid Cation and Pt(CN)4 Anion Salt: Synthesis, Structural Properties, Hirshfeld Surface Analysis and Density Functional Theory Calculations
- Author
-
Resul Sevinçek, Elif Gungor, and Hülya Kara Subasat
- Subjects
chemistry.chemical_classification ,chemistry.chemical_compound ,Chemistry ,Polymer chemistry ,Pyridine ,Fizik, Uygulamalı ,Salt (chemistry) ,Boroxine compound,DFT calculations,Hirshfeld surface analysis ,Density functional theory ,Boronic acid ,Ion ,Physics, Applied - Abstract
In this work, the novel compound [HNC5H4B(OH)2-4][Pt(CN)4] (1) has been synthesized and structurally characterized. The compound (1) crystallizes in monoclinic, space group P21/c, a=5.6159(11) Å, b=14.656(3) Å, c=11.619(2) Å, 𝛼=90, β= 110.35(3), γ=90, V= 896.6(3) Å3, Z=2. The optimum molecular geometry parameters have been investigated with the DFT/B3LYP method. All geometric parameters are found in good agreement with crystallographic and computational results. Contributions of fragments molecular orbitals (HOFO-LUFO) to frontier molecular orbitals (HOMOLUMO) are calculated charge transferred from Pt moiety to other fragments.
- Published
- 2021
38. nvestigation of interactions of selected plant-based active molecules with nucleobases and some nucleotide sequences using bioinformatic and computational tools
- Author
-
Şener Raman, Tuğçe, Açar Selçuki, Nursel, and Ege Üniversitesi, Fen Bilimleri Enstitüsü, Biyoteknoloji Ana Bilim Dalı
- Subjects
Nükleotid ,Yoğunluk Fonksiyoneli Teorisi ,Molecular Modeling ,Moleküler Modelleme ,Luteolin, Nucleotide ,Luteolin ,Density Functional Theory ,miR-155 - Abstract
Bu tez çalışmasında, bitkisel aktif molekül olan Luteolin molekülü ile nükleoidler (dAMP, dCMP, dGMP ve dTMP) arasındaki etkileşimlerin bağlanma bölgeleri, enerjileri ve konformerlerindeki değişikliklerin incelenmesi ve Luteolin ile nükleotid dimerlerinden elde edilen sonuçlar doğrultusunda sistematik olarak miR-155 ile Luteolin arasındaki etkileşimlerin bağlanma bölgelerinin saptanması amaçlanmıştır. Hesapsal çalışmada, öncelikle Luteolin ve nüklotidlerin detaylı konformasyonel analizi yapılmıştır. Konformasyonel analizden elde edilen konformerler su fazında ωB97XD/6-31+G(d,p) seviyelerinde optimizasyon prosedürleri kullanılarak elektronik enerji hesaplanmıştır ve en kararlı yapılar belirlenmiştir. Luteolin molekülü ile nükleotid molekülleri arasındaki kompleks oluşumları belirlenerek, kompleksler arasındaki bağlanma bölgeleri, kuvvetleri ve aralarında meydana gelen yük geçişleri hesaplanmıştır. Nükleotidler arasında en kararlı Luteolin-dCMP kompleksi olarak bulunmuştur. Deneysel çalışmada ise, Luteolin, dCMP ve Luteolin-dCMP kompleksi'nin UV/Vis spektroskopisi, floresans spektroskopisi ve voltametri ölçümlerin yapılarak deneysel ve hesapsal veriler karşılaştırlmıştır. Ayrıca, biyolojik modellerde bu kapsamda Lutolin molekülü ile miR-155 dizisi olası etkileşim bölgeleri için öneride bulunulmuştur., In this thesis, it was aimed to investigate the changes in the binding sites, energies, and conformers of the interactions between the herbal active molecule Luteolin and nucleoids (dAMP, dCMP, dGMP and dTMP), and systematically determine the binding sites of the interactions between miR-155 and Luteolin in line with the results obtained from Luteolin and nucleotide complex. In the computational study, the first, a detailed conformational analysis of luteolin and nucleotides was performed. Electronic energy was calculated using optimization procedures at ωB97XD/6-31+G(d,p) levels in the water phase of conformers obtained from the conformational analysis and the most stable structures were determined. By determining the complex formations between the Luteolin molecule and the nucleotide molecules, the binding sites between the complexes, their energies, and the charge transitions between them were calculated. Among the nucleotides, it has been found to be the most stable Luteolin-dCMP complex. In the experimental study, UV/Vis spectroscopy, fluorescence spectroscopy, voltammetry measurements of Luteolin, dCMP, and Luteolin-dCMP complex were performed, and then experimental and computational data were compared. Finally, in biological models, possible interaction sites of the Luteolin molecule and the miR-155 sequence have been suggested.
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- 2021
39. Keto grubu içeren piridazin türevi bazı bileşiklerden sentezlenmiş tek kristallerin yapılarının çeşitli spektroskopik ve hesaplamalı yöntemlerle aydınlatılması
- Author
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Baydere, Cemile, Dege, Necmi, and OMÜ, Lisansüstü Eğitim Enstitüsü, Hayvan Besleme ve Beslenme Hastalıkları Ana Bilim Dalı
- Subjects
FT-IR ,pyridazine ,X-ışını kırınımı yöntemi ,piridazin ,UV-vis ,Hirshfeld surface analysis ,yoğunluk fonksiyoneli kuramı ,Hirshfeld yüzey analizi ,X-ray diffraction method ,density functional theory ,thermal analysis ,termal analiz - Abstract
Bu tez çalışmasında sekiz adet piridazin bileşiği sentezlenmiştir. Sentezlenen kristallerin kırınım verileri Ondokuz Mayıs Üniversitesi Fizik Bölümü Kristalografi Laboratuvarındaki STOE IPDS−II difraktometresi kullanılarak elde edilmiştir. Kristallerin yapı çözümleri, WinGX paket programı içindeki SHELXT−2018/1 yazılımı ile direkt yöntemler kullanılarak belirlenmiştir. Atomik parametreler SHELXL−2018/3 ile tam matris en küçük kareler yöntemi ve fark Fourier yöntemleri kullanılarak arıtılmıştır. Sentezlenmiş sekiz kristalin deneysel ve kuramsal olarak birim hücre paket diyagramları, hidrojen bağı geometrileri, bağ uzunlukları, bağ açıları ve torsiyon açıları elde edilmiştir. X-ışını kırınımı verilerinden ve YKF/B3LYP/6−311G++(d,p) yöntemi kullanılarak elde edilen bağ uzunlukları, bağ açıları ve torsiyon açıları değerleri karşılaştırılmıştır. Karşılaştırılan bu deneysel ve kuramsal sonuçların birbirleriyle oldukça uyumlu olduğu görülmüştür. Crystal Explorer 17.5 programı kullanılarak tüm yapıların Hirshfeld yüzeyi belirlenerek molekül içi, moleküler arası etkileşimler araştırılmış ve parmak izi haritaları elde edilmiştir. Deneysel olarak X-ışını kırınımından ve kuramsal olarak Hirshfeld yüzey analizi çalışmalarından elde edilen molekül içi ve moleküller arası etkileşimler karşılaştırılmıştır. Karşılaştırılan bu değerlerin oldukça uyum içerisinde olduğu görülmüştür. Ayrıca kristallerin moleküler enerjileri, moleküler elektrostatik potansiyel haritaları ve sınır yörüngemsileri (HOMO, LUMO) YKF/B3LYP/6−311G++(d,p) hesaplama yöntemi kullanılarak kuramsal olarak incelenmiştir. Sentezlenmiş bazı bileşiklerin deneysel ve kuramsal olarak IR spektrumları belirlenmiştir ve bu spektrumların birbirlerine karşı kıyaslanmaları yapılmıştır. Karşılaştırılan deneysel ve kuramsal IR spektrumlarının birbiriyle oldukça uyum içerisinde olduğu görülmüştür. Sentezlenmiş bazı bileşiklerin deneysel ve kuramsal olarak UV-vis spektrumları belirlenmiştir ve bu spektrumların birbirlerine karşı kıyaslanmaları yapılmıştır. Karşılaştırılan deneysel ve kuramsal UV-vis spektrumlarının birbiriyle oldukça uyum içerisinde olduğu görülmüştür. Kuramsal IR ve UV-vis hesaplamaları için YKF/B3LYP/6−311G++(d,p) baz seti seçilmiştir. Son olarak sentezlenmiş bazı kristallerin TGA/DTA analizleri yapılmıştır. In this thesis study, eight pyridazine compounds have been synthesized. The diffraction data of these synthesized crystals were obtained using the STOE IPDS−II diffractometer at the Ondokuz Mayıs University Physics Department Crystallography Laboratory. Structural solutions of crystals were determined using direct methods with SHELXT−2018/1 software in WinGX package program. Atomic parameters were refined with SHELXL−2018/3 using full matrix least squares method and difference Fourier methods. Unit cell packet diagrams, hydrogen bond geometries, bond lengths, bond angles and torsion angles of eight synthesized crystals were obtained experimentally and theoretically. The bond lengths, bond angles and torsion angle values obtained from X-ray diffraction data and using the DFT/B3LYP/6−311G++(d,p) method were compared. It has been seen that these experimental and theoretical results compared are quite compatible with each other. By using the Crystal Explorer 17.5 program, the Hirshfeld surface of all structures was determined, and intramolecular and intermolecular interactions were investigated and fingerprint maps were obtained. Intramolecular and intermolecular interactions obtained experimentally from X-ray diffraction and theoretically obtained from Hirshfeld surface analysis studies were compared. These compared values has been seen to be in good agreement. In addition, the molecular energies, molecular electrostatic potential maps and boundary orbitals (HOMO, LUMO) of the crystals were theoretically investigated using the DFT/B3LYP/6−311G++(d,p) calculation method. Experimentally and theoretically IR spectra of some synthesized compounds were determined and these spectra were compared against each other. The experimental and theoretical IR spectra compared has been seen to be in good agreement with each other. Experimentally and theoretically UV-vis spectra of some synthesized compounds were determined and these spectra were compared against each other. The experimental and theoretical UV-vis spectra compared has been seen to be in good agreement with each other. The DFT/B3LYP/6−311G++(d,p) base set was chosen for the theoretical IR and UV-vis calculations. Finally, TGA/DTA analyzes of some synthesized crystals were made.
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- 2021
40. The investigation of the basic physical properties of some X2YZ type full-heusler compounds using first principles methods
- Author
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Şahin, Halil, Çoban, Cansu, and Fen Bilimleri Enstitüsü
- Subjects
Electronic Properties ,Thermodynamic Properties ,Co2YGe(Y=Fe, Sc, Ti) Tam Heusler Bileşikleri ,Phonon Properties ,Elektronik Özellikler ,Fonon Özellikleri ,Yoğunluk Fonksiyonel Teorisi ,Method of First Principles ,Co2YGe(Y=Fe, Sc, Ti) Full-Heusler Compounds ,Elastic Properties ,Termodinamik Özellikler ,İlk İlkeler Yöntemi ,Elastik Özellikler ,Density Functional Theory - Abstract
Balıkesir Üniversitesi, Fen Bilimleri Enstitüsü, Fizik Ana Bilim Dalı., X2YZ (L21) yapıdaki Co2YGe(Y=Fe, Sc, Ti) tam-Heusler bileşiklerinin yapısal, elektronik, elastik, titreşimsel ve termodinamik özellikleri ilk ilkeler yöntemiyle incelenmiştir. E-V eğrileri kullanılarak öncelikle P=0 GPa'da örgü sabiti (a0), bulk modülü (B0) ve bulk modülünün türevi (B0') hesaplanmıştır. Sonuçlar literatürdeki mevcut bulgularla uyumludur. Bileşiklerin elektronik bant ve durum yoğunluğu (DOS) grafikleri, Zener anizotropi faktörü, Young modülü, vs. gibi elastik özellikleri bulunmuş ve sunulmuştur. Elastik özellikler basınç altında da incelenmiştir. Sonuçlar, Co2FeGe'un daha düşük, diğer malzemelerin ise daha yüksek basınçlarda da kararlı olduğunu göstermektedir. Elde edilen fonon dağılım eğrilerinde tüm frekanslar pozitif olduğundan Co2YGe(Y=Fe, Sc, Ti) bileşikleri dinamik olarak da kararlıdır. Fonon sonuçlarından faydalanılarak hesaplanan termodinamik sonuçlar da çalışmanın son kısımda ele alınarak açıklanmıştır., The structural, electronic, elastic, vibrational, and thermodynamic properties of Co2YGe(Y=Fe, Sc, Ti) full-Heusler compounds in X2YZ (L21) structure were investigated by the method of first principles. Using the E-V curves, firstly, the lattice constant (a0), bulk modulus (B0), and derivative of bulk modulus (B0’) were calculated at P = 0 GPa. The results are consistent with the available findings in the literature. The electronic band and density of state (DOS) graphs of the compounds, the elastic properties of the compounds such as Zener anisotropy factor, Young's modulus, etc. were found and presented. Elastic properties have also been studied under pressure. The results show that Co2FeGe is stable at lower pressures, while other materials are also stable at higher pressures. Since all frequencies are positive in the obtained phonon dispersion curves, Co2YGe(Y=Fe, Sc, Ti) compounds are also dynamically stable. The thermodynamic results calculated using the phonon results were also discussed and explained in the last part of the study.
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- 2021
41. Halojen Atomları ve Siyano Grubunun Hekzasen Molekülünün Optik, Elektronik ve Yük Transfer Özellikleri Üzerine Etkisinin İncelenmesi: Moleküler Dizayn Yöntemi, Yapı-Özellik İlişkisi
- Author
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Gül Yakali
- Subjects
Science (General) ,Materials science ,reorganizasyon enerji ,Substituent ,Fizik, Uygulamalı ,General Medicine ,yoğunluk fonksiyon teorisi ,marcus teori ,Hexacene ,Marcus theory ,Physics, Applied ,Q1-390 ,Crystallography ,chemistry.chemical_compound ,Molecular geometry ,Electron affinity (data page) ,chemistry ,elektron afinitesi ,i̇yonizasyon potansiyeli ,yük taşıma oranı ,Molecule ,Density functional theory ,Charge carrier ,İyonizasyon potansiyeli,Yoğunluk fonksiyon teorisi,Elektron afinitesi,Reorganizasyon enerji,Marcus teori,Yük taşıma oranı ,Density functional theory,Iyonization potential,Electron affinity,Reorganization energy,Marcus theory,Charge carrier rate - Abstract
Bu çalışmada, π-konjugasyon yapısına sahip hekzasen molekülü, farklı halojen atomlar (Flor, Klor, Brom) ve molekülde farklı konumlandırılmış siyano grupları ile dizayn edilmiş, elektronik, optik ve yük transfer özellikleri zamana bağlı ve zamandan bağımsız Yoğunluk Fonksiyon Teorisi (YFT) ile incelenmiştir. Dizayn edilen beş hekzasen türevinin yapı ve özellik arasındaki ilişkiyi kurabilmek için, moleküler geometri, reorganizasyon enerji, HOMO-LUMO orbital enerjileri, iyonizasyon potansiyeli (IP), elektron afinitesi (EA), geometriden dolayı nötr ve yüklü durumlara bağlı olarak bağ uzunluğu değişimi (BUD) üzerine substitüe etkisi incelenmiş ve etkiyi daha iyi anlayabilmek için sonuçlar hekzasen ve antrasen moleküllerin sonuçlarıyla karşılaştırılmıştır. Moleküllerin, elektron enjeksiyon bariyerinin hekzasen molekülünden daha düşük olduğu ve iyi bir boşluk taşıyıcısı olarak bilinen antrasenle kıyaslanabilir derecede etkili boşluk yük transfer oranına sahip olduğu belirtilmiştir. Dizayn edilen hekzasen türevlerinin, optoelektronik alanda potansiyel uygulamalar için ilgi çekebileceğini ve malzeme biliminde umut vaad edeceğini umuyorum., In this study, the π-conjugated hexacene molecule was designed with different halogen atoms (Fluorine, Chlorine, Bromine), differently positioned cyano groups and its electronic, optical and charge transfer properties were investigated by time-dependent and time-independent Density Functional Theory (DFT). The substituent effect on the molecular geometry, reorganization energy, frontier orbitals, ionization potential (IP) and bond length alternation (BLA) depending on nötr and charged states, electronic affinity (EA) of the five molecules were investigated to establish the relationship between structures and properties .To gain a better understanding of the substituent effect on the charge transport property, the results of designed molecules were compared with hexacene and antracene molecules. The electron injection barrier of the new designed molecules is lower than hexacene molecule and have more effective hole charge transfer property which is comparable to that of antracene known as a good hole charge carrier. I belived that, new designed hexacene derivatives may be used as optoelectronic devices which could attract great attention in material sciences.
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- 2020
42. Investigation of the effects of molecular doping on the molecular structure and electrical conductivity of DNA
- Author
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Akın, Çağlanaz, Ören, Ersin Emre, TOBB ETÜ, Fen Bilimleri Enstitüsü, TOBB Ekonomi ve Teknoloji Üniversitesi Fen Bilimleri Enstitüsü, Mikro ve Nanoteknoloji Lisansüstü Programı, and TOBB University of Economics and Technology Graduate School of Engineering and Science, Micro and Nanotechnology Graduate Programs
- Subjects
Moleküler katkılama ,İlaç-DNA etkileşimleri ,Molecular electronics ,Yük taşınımı ,DNA ,Molecular dynamics ,Charge transport ,Drug-DNA interactions ,Moleküler elektronik ,Theory and modeling ,Teori ve modelleme ,Molecular doping ,Density functional theory ,Intercalation ,Yoğunluk fonksiyonel teorisi ,İnterkalasyon ,Moleküler dinamik - Abstract
Tek bir molekülün üzerinden geçen elektrik akımı ölçülebildiği zamandan bu yana moleküler elektronik alanında çalışmalar hız kazanmıştır. Bu çalışmaların genel amacı, yeni nesil entegre devrelerde kullanılmak üzere elektronik cihazların işlem hızını ve hafızasını arttırmaya yönelik geliştirilecek teknolojiler için bilgi birikimi oluşturmaktır. Bu tez kapsamında bahsedilen bilgi birikimine katkı sağlamak amacıyla, moleküler katkılamaların DNA'nın moleküler yapısı ve elektriksel iletkenliği üzerindeki etkileri incelendi. DNA'yı moleküler olarak katkılamanın en bilinen yolu DNA'yı hedefleyen antikanser, antiparaziter ve antibiyotik ilaçları kullanmaktadır. Bu tez kapsamında sensör teknolojisine ve ilaç-DNA etkileşimlerinin anlaşılmasına da katkı sağlamak amacıyla moleküler katkılamalar ilaç molekülleriyle yapılmıştır. Moleküler yapı incelemeleri için AMBER 16 programı kullanılarak moleküler dinamik simülasyonları yapıldı. Simülasyon süresince meydana gelen değişimleri incelemek adına; yapıların referans formlara benzerlikleri, DNA'nın baz çiftleri arasındaki hidrojen bağları ve DNA dizilimindeki pürinler arası mesafeler hesaplandı. Kümeleme algoritması kullanılarak her simülasyonu temsil eden bir temsilci yapı seçildi. Temsilci yapının kuantum mekaniksel özellikleri DFT yardımıyla hesaplanırken Gaussian 09 programı kullanıldı. Elde edilen sonuçlar v kullanılarak yapıların bant diyagramları elde edildi. Ardından her yapı için yük taşınım olasılıkları hesaplandı. Yapılan çalışmalar sonucunda, farklı moleküler katkılamaların DNA'nın moleküler yapısını ve elektriksel iletkenliğini farklı etkilediği gösterildi. Tez kapsamında yapılan çalışmanın moleküler elektronik alanında katkı sağlamasının yanı sıra ilaç testi adı verilen ölçümler için ileride geliştirilebilecek sensör teknolojilerine de katkı sağlaması beklenmektedir., Many studies have done in the field of molecular electronics since the ability of measuring the electrical current through a single molecule. These studies generally aim to create knowledge to develop the technologies which aims to increase the calculation speed and memory of electronic devices to be used in integrated circuits. In this thesis, contributing to this knowledge is aimed and effects of molecular doping on the molecular structure and electrical conductivity of DNA are investigated. The most known way to dope the DNA is the usage of anticancer, antiparasitic and antibiotic drugs which already target the DNA. In this thesis, doping were done using drug molecules to contribute the sensor technologies and understanding of drug-DNA interactions too. To investigate the molecular structures, molecular dynamics simulations were done with AMBER 16 software program. To examine the molecular structure changes among simulation time; similarities between the structures and reference structures, hydrogen bonding between DNA base pairs and the distances between purines in the DNA sequence are calculated. With clustering algorithm, representative structures were choosen from simulations. Gaussian 09 software program was used to calculate quantum mechanichal properties of representative structures and band diagrams of the structures were analyzed. Later, charge transport vii probabilities were calculated for all structures. Results showed that, various molecular doping have different effect on both molecular structure and electrical conductivity of DNA. This thesis may contribute to sensor technologies for drug screening as well as molecular electronics.
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- 2020
43. Investigation of ozonolysis of unsaturated acids in aqueous solution by molecular modeling
- Author
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Qaroot, Sulaiman Mohammed Sulaiman, Selçuki, Cenk, and Fen Bilimleri Enstitüsü
- Subjects
Ozonolysis ,Ozonoliz ,Yoğunluk Fonksiyoneli Teorisi ,Unsaturated Acid ,Doymamış Asit ,Gaussian16 ,Density Functional Theory - Abstract
Ozonoliz tepkimesi ozonun doymamış karbon-karbon bağları ile tepkimesi olarak tanımlanır. Bu tepkime gaz fazında veya sulu çözeltide gerçekleşebilir. Organik tepkmelerde yaygın olarak kullanılan bir tepkime türüdür. Ayrıca sulu ortamda kirleticilerin bozundurulması amacı ile de yaygın olarak kullanılmaktadır. Bu çalışmada biyokimyasal açıdan önem taşıyan ve canlı sistemlerde yer alan ve/veya canlılarla doğrudan temas halinde bulunan doymamış asitlerin (akrilik asit, metakrilik asit, maleik asit) konformasyonel analizi Spartan 16 programı kullanarak yapıldı. Bulunan konformerlerin optimizasyonu ve frekans analizi hesaplamaları Gaussian16 yazılımında bulunduğu şekliyle B3LYP/6-311++G(d,p) seviyesinde gerçekleştirildi. Optimize edilmiş doymamış asitlerin tüm konformerlerinin ozon ile olan tepkime mekanizmalarının önce gaz fazında daha sonra sulu çözeltide hesaplamaları yapıldı. Rölatif enerji değerleri hesaplanarak yapıların enerji diyagramları oluşturuldu. Tüm sistemlerin yapıları, elektronik ve termodinamik özellikleri hem eş zamanlı hem basamaklı tepkime mekanizmaları için incelenerek sonuçlar değerlendirildi. Hesaplamalar FenCluster (Ege Üniversitesi Fen Fakültesi) ve TÜBITAK-ULAKBİM Truba kaynakları kullanılarak gerçekleştirilmiştir., Ozonolysis is described as the reaction of ozone with unsaturated carbon-carbon double bonds. The reaction may take place in gas phase as well as in aqueous phase. It is one of the reactions used in organic synthesis. Additionally, it is one of the reactions used to degrade the pollutants in water environment. In this study, the conformational analysis of unsaturated acids (acrylic acid, methacrylic acid, maleic acid), which are biochemically important and/or directly in contact with living organisms, was performed using the Spartan 16 program. The calculations on optimization and frequency analysis of the conformers were performed at B3LYP/6-311 ++G(d, p) level as implemented in Gaussian16. The reaction mechanisms of all conformers of optimized unsaturated acids with ozone were first calculated in the gas phase and then in aqueous solution. The energy diagrams of the structures were generated by calculating the relative energy values. The structures, electronic and thermodynamical properties of all studied systems investigated by using both concerted and stepwise reaction mechanisms are reported and the results were evaluated. Computer time on FenCluster (Faculty of Science, Ege University) and TÜBİTAK-ULAKBİM Truba Resources is gratefully acknowledged.
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- 2020
44. Investigation of Schiff bases present in biological systems on model systems by computational methods
- Author
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Ürgenç Türkay, Gülin, Selçuki, Cenk, and Fen Bilimleri Enstitüsü
- Subjects
Isatin ,Schiff Base ,Reaksiyon Mekanizması ,Yoğunluk Fonksiyoneli Teorisi ,Lysine ,Lizin ,Molecular Modeling ,Moleküler Modelleme ,Schiff Bazı ,Reaction Mechanism ,İsatin ,Density Functional Theory - Abstract
Bu tezde biyolojik model sistemlerde lizin ve bazı isatin türevlerinin Schiff bazı oluşum mekanizmalarının hesapsal yöntemlerle incelenmesi amaçlanmıştır. Muhtemel yüklü ve kanonik lizin yapıları ile literatürdeki bilgiler ile belirlenen isatin türevlerinin detaylı konformasyonel analizi yapılmıştır. Konformasyonel analizden elde edilen konformerler B3LYP/cc-PVTZ ve ωB97XD/cc-PVTZ seviyelerinde tamamen optimize edilmiş ve frekans analizinin öznesi olmuşlardır. Bu optimize olan lizin ve isatin yapıları, yukarıda belirtilen seviyelerde, Schiff bazı oluşum reaksiyon mekanizması önermek için kullanılmıştır. Lizin-isatin Schiff bazı oluşum reaksiyon mekanizmasının potansiyel enerji yüzeyindeki reaksiyon koordinatları, farklı optimizasyon prosedürleri kullanılarak elektronik enerji, dipol moment, harmonik titreşim frekansları hesaplanmıştır. Sonuç olarak, fizyolojik koşullarda ve nötral reaksiyon koşulları için, biyolojik modellerde lizin ve imin bağının önem arzettiği, basamaklı bir mekanizma önerisi yapılmıştır. Anahtar sözcükler: Lizin, İsatin, Schiff Bazı, Yoğunluk Fonksiyoneli Teorisi, Moleküler Modelleme, Reaksiyon Mekanizması., The aim of the study to investigate the reaction mechanism of Schiff base formation between lysine and some isatin derivatives in biological model systems by using computational methods. Detailed conformational analysis has been carried out for possible charged and canonical lysine structures along with isatin derivatives, that have been determined from literature. Conformers that have been obtained from conformational analysis, were fully optimized and subjected to a frequency analysis at B3LYP/cc-PVTZ and ωB97XD/cc-PVTZ levels of theory. Fully optimized structures of lysine and isatin derivatives have been used for proposing Schiff base formation reaction mechanism at same levels of theory mentioned as above. Reaction coordinates at potential energy surface of lysine-isatin Schiff base formation mechanism have been computed by different optimization procedures. In conclusion, at physiological conditions and for neutral reaction conditions, a stepwise reaction mechanism isa proposed based on lysine and imine bond formation reaction in biological models. Keywords: Lysine, Isatin, Schiff Base, Density Functional Theory, Molecular Modeling, Reaction Mechanism.
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- 2020
45. [Ni(2-Benzimidazol-il-üre)2(etanol)2][NO3]2 Bileşiğinin Yoğunluk Fonksiyoneli Teorisi Kullanılarak Yapılan Bazı Kuantum Kimyasal Hesaplamaları
- Author
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Mehmet Poyraz and Zeynep Turhan Irak
- Subjects
Physics ,moleküler parametreler ,Engineering, Chemical ,Gaussian ,molecular parameters ,General Medicine ,Electronic structure ,dft ,Mühendislik, Kimya ,symbols.namesake ,Dipole ,Atomic orbital ,benzimidazoly-urea ,Molecular property ,symbols ,Molecule ,Physical chemistry ,Benzimidazoly-urea,Molecular parameters,DFT ,Density functional theory ,yft ,lcsh:Science (General) ,Single crystal ,benzimidazol-il-üre ,lcsh:Q1-390 ,Benzimidazol-il-üre,Moleküler parametreler,YFT - Abstract
Bu çalışmada, moleküler yapısı tek bir kristalX-ışınım yöntemi ile belirlenen [Ni(2-Benzimidazol-il-üre)2(etanol)2][NO3]2bileşiğinin teorik hesaplamaları yapılmıştır. Teorik hesaplamalarda elde edilenoptimize geometri, dipol moment gibi birçok özellik deneysel değerlere oldukçayakın sonuçlar göstermiştir. Bunların dışında bileşiğin gaz fazında sınırorbitalleri, hesaplanan sınır orbitallerin enerjilerinden elektronik yapıtanımlayıcıları, moleküler elektrostatik potansiyel haritası, doğrusal olmayanoptik özellikleri hesaplanmış ve yorumlanmıştır. Çalışmanın birçok organometal kompleksinmoleküler özelliğine ışık tutacağı düşünülmektedir. Yoğunluk FonksiyonelTeorisi (YFT), Gaussian 09W programı kullanılarak hesaplama yöntemi olarakseçilmiştir ve kompleks için B3LYP/LANL2DZseviyesinde optimize edilmiş gaz faz kuantum mekaniksel verileri eldeedilmiştir., Thetheoretical calculations of the [Ni(2-Benzimidazoly-urea)2(ethanol)2][NO3]2 compound, whose molecular structure was determinedwith a single crystal X-ray diffraction method, was conducted. Many propertiessuch as optimized geometry and dipole moment obtained in theoreticalcalculations showed very approximate to experimental values. Apart from these,the frontier orbitals of the compound in the gas phase, the electronicstructure parameters from the energies of the calculated frontier orbitals,molecular electrostatic potential map, non-linear optical properties were calculatedand interpreted. It is thought that the study will shed light on the molecularproperty of many organometal complexes. The Density Functional Theory (DFT) wasselected as a computational method using the Gaussian 09W program, and theoptimized gase phase quantum mechanical data for the complex was obtained inthe B3LYP/LANL2DZ level with genkeyword.
- Published
- 2019
46. Bazı alkali tabanlı tam-heusler malzemelerin termoelektrik özelliklerinin temel ilkeler ile incelenmesi
- Author
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Yazıcı, Oğuzhan, Gürel, Tanju, and Fizik Anabilim Dalı
- Subjects
Ther moelectric properties ,Yoğunluk fonksiyonel kuramı ,Fizik ve Fizik Mühendisliği ,Tam-heusler malzemeler ,Density functional theory ,Ab initio calculations ,Full-heusler ,Physics and Physics Engineering ,Termoelektrik özellikler ,Ab initio hesaplamalar - Abstract
Küresel enerji kullanımının verimliliğini artırmak için olası yollar arasında, termoelektrik önemli bir seçenektir. Dahili bir sıcaklık gradyanını gerilime dönüştüren termoelektrik malzemeler, soğutmada ve atık ısıdan güç üretme uygulamalarında kullanılır. Termoelektrik malzemelerin performansı, yüksek bir Seebeck katsayısı (S), yüksek elektriksel iletkenlik (s) ve düşük termal iletkenliği (k) gerektiren termoelektrik de?ger (ZT) ile karakterize edilir. Tam-Heusler (X2YZ) malzemeleri düşük maliyetli elemanlardan türetilmeleri, mekanik güvenilirlik ve çalı¸sma koşullarında ısıl kararlılıklarından dolayı atık ısı termoelektrik uygulamaları için özellikle ilgi çekicidir. Tam-Heusler malzemelerin bu gibi özelliklerinden dolayı, bu çalışmada Li2NaSb, Li2NaBi, K2CsSb ve K2CsBi Tam-Heusler bileşiklerinin, Seebeck katsayıları, güç faktörleri, elektriksel iletkenlik, elektronik ve örgü termal iletkenlik gibi özellikleri hesaplanmış ve bu malzemelerin termoelektrik performansı incelenmiştir. Yaptığımız hesaplarda Yoğunluk fonksiyonel kuramı kapsamında düzlem dalga ve sanal-potansiyeller kullanılmış olup, değiş-tokus ve korelasyon enerjisi için genelleştirilmiş gradyan yaklaşımı kullanılmıştır. Genelleştirilmiş gradyan yaklaşımı’ndaki değiş-tokuş ve korelasyon fonksiyoneli için ise Perdew, Burke ve Ernzerhof’un birlikte geliştirdikleri form kullanılmıştır. Termoelektrik katsayılar ise sabit gevşeme zamanı yaklaşımı altında yarı-klasik Boltzmann taşınım denklemi çözülerek hesaplanmıştır. Çalışılan malzemeler içerisinde p-tipi K2CsSb’nin yüksek Seebeck katsayısına ve düşük örgü termal iletkenliğe sahip olduğu bulunmuş ve 600 K’den büyük sıcaklıklarda ZT değerinin 2’den büyük olduğu öngörülmüştür. Among the possible ways to increase the efficiency of global energy use, thermoelectric is an important option. Thermoelectric materials that convert an internal temperature gradient to voltage are used in cooling and waste heat power generation applications. The performance of thermoelectric materials is characterized by a high Seebeck coefficient (S), high electrical conductivity (s) and a thermoelectric value (ZT) requiring low thermal conductivity (k). Full-Heusler (X2YZ) materials are particularly interesting for waste heat thermoelectric applications due to their deriving from low-cost elements, mechanical reliability and thermal stability under operating conditions. In this study, properties of Li2NaSb, Li2NaBi, K2CsSb and K2CsBi Full-Heusler compounds such as Seebeck coefficients, power factors, electrical conductivity, electronic and lattice thermal conductivity were calculated and the thermoelectric performance of these materials were investigated. Plane waves and pseudo-potentials are used within the scope of density functional theory and generalized gradient approach is used for exchange-correlation energy. In the generalized gradient approach, the form developed by Perdew, Burke, and Ernzerhof was used for the exchange-correlation functional. Thermoelectric coefficients were calculated by solving the semi-classical Boltzmann transport equation under the constant relaxation time approach. It has been found that p-type K2CsSb has high Seebeck coefficient and low lattice thermal conductivity in the materials studied and it is assumed that ZT value is greater than 2 at temperatures greater than 600 K.
- Published
- 2019
47. Metal halojenür Agl bileşiğinin çinkoblend, würtzite ve kaya- tuzu fazlarının termoelektrik özelliklerinin temel ilkeler ile incelenmesi
- Author
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Beceren, Berna
- Subjects
Termoelektrik verim ,yoğunluk fonksiyonel kuramı ,Figure of merit ,Ab initio calculations ,termoelektrik özellikler ,thermoelectric properties ,density functional theory ,Ab initio hesaplamalar - Abstract
Bu tez çalışmasında AgI’nın würtzite ve çinkoblend fazları için P=0 GPa basınç altında ve kaya-tuzu fazı için üç farklı P=0 GPa, P=2 GPa, P=10 GPa basınç altında ve spin-orbit etkileşmesinin dahil edildiği ve edilmediği durumlar için; kristal yapıları, elektronik bant yapıları, fonon dağılımları ve fonon durum yoğunlukları ile ta¸sıyıcı konsantrasyonu ile sıcaklığın fonksiyonu olarak p-tipi ve n-tipi katkılama için; Seebeck katsayıları, elektriksel iletkenlikleri, güç faktörleri elektronik termal iletkenlikleri gibi termoelektrik özellikleri temel ilkelere göre hesaplanmıştır. Tüm fazlar için, sabit gevşeme zamanı yaklaşımı altında yarı-klasik Boltzmann taşınım denklemi çözülerek ve literatürdeki örgü termal iletkenlik katsayıları dikkate alınarak, yapılan fayda faktörü(ZT) hesabı sonucunda dikkate değer ¸sekilde AgI’nın kaya-tuzu fazı için P = 2 GPa basınç altında n-tipi katkılama için ZT = 1:5 iken p-tipi için yakla¸sık ZT = 2:1 de?geri elde edilmiştir. Uygulama açısından termoelektrik malzemelerde ZT>1 de?gerde olması gerektiğinden hareketle bu çalışmada basınç altındaki kaya-tuzu AgI fazının termoelektrik açıdan umut vaad edici olduğu gösterilmiştir. In this thesis, the crystal structures, electronic band structures, phonon distributions and phonon density of states and thermoelectric properties such as Seebeck coefficients, electrical conductivity, electronic thermal conductivity and power factors of AgI were calculated using ab-initio methods for the würtzite and zincblend phases under P = 0 GPa pressure and for the rock-salt phase under three different P = 0, 2, and 10 GPa pressures with or without spin-orbit interaction and for p-type and n-type doping as a function of temperature. For all phases, using semi-classical Boltzmann transport equation under the constant relaxation time approach and considering the lattice thermal conductivity coefficients in the literature, the figure of merit(ZT) calculations result in remarkable values of ZT = 1:5 under the pressure of P = 2 GPa for n-type dopping and ZT = 2:1 for the p-type doping in the rock-salt phase. Since thermoelectric materials should have a value of ZT > 1 for practical applications, the rock-salt phase of AgI under pressure can be considered as a thermoelectrically promising material
- Published
- 2019
48. Ag8SnS6 ve Ag8SnSe6 argirodit bileşiklerinin elektronik, taşınım ve termoelektrik özelliklerinin temel ilkeler ile incelenmesi
- Author
-
Güngör, Elif Fatma, Yıldırım, Serbülent, Gürel, Tanju, and Fizik Anabilim Dalı
- Subjects
silver based semiconductors ,Fizik ve Fizik Mühendisliği ,gümüş tabanlı yarıiletkenler malzemeler ,yoğunluk fonksiyonel kuramı ,Ab initio calculations ,Physics and Physics Engineering ,termoelektrik özellikler ,thermoelectric properties ,density functional theory ,Ab initio hesaplamalar - Abstract
Termoelektrik sistemler çevre dostu ve yenilenebilir enerji özellikleriyle tercih edilebilir sistemlerdir. Farklı avantajlarıyla termoelektrik enerji uygulamaları soğutma, ısıtma, elektrik üretimi ve iklimlendirme gibi çeşitli alanlarda yaygınlaşma potansiyeli vardır. Termoelektrik metaryellerin verimliliği yüksek elektriksel iletkenlik ve Seebeck katsayısı ve düşük termal iletkenliğe sahip olması gerekmektedir. Aynı anda tüm bu özelliklere sahip malzemeler çok az miktardadır. Ag8SnS6 ve Ag8SnSe6 malzemeleri düşük termal iletkenliğe sahip olduğu bilinen yüksek düzensizliğe sahip yarıiletkenler olup elektronik ta¸sınım özelliklerinden dolayı dikkat çekmektedirler. Bu çalışmada Ag8SnS6 ve Ag8SnSe6 yarıiletkenlerin yapısal, elektronik ve termoelektrik özellikleri temel ilke yöntemleriyle incelenmişve sonuçlar mevcut deneyler ile karşılaştırılmıştır. Hesaplamalar yoğunluk fonksiyonel kuramı ve yarı-klasik Boltzmann taşınım kuramı ile gerçekleştirilmiştir. Örgü sabitleri, hacim modülü, elektronik bant yapıları, toplam ve kısmi durum yoğunlukları ve termoelektrik katsayıları deneyden hiç bir parametre kullanılmadan hesaplanmıştır. Hesaplamalar sonucu elde edilen ZT öngörüleri var olan n-tipi katkılanmış deneylerle uyumlu olup, p-tipi katkılama yapıldığında ZT değerlerinin çok daha yüksek olacağı bulunmuştur Thermoelectric systems are preferable systems with environmental friendly and renewable energy properties. Thermoelectric power applications with different advantages have the potential to expand in various fields such as cooling, heating, electricity generation and air conditioning. Thermoelectric materials must have high electrical conductivity and high Seebeck coefficient and low thermal conductivity. Few materials exist having all these features at the same time. Ag8SnS6 and Ag8SnSe6 materials are highly disordered semiconductors which are known to have low thermal conductivity and attract attention due to their electronic transport properties. In this study, structural, electronic and thermoelectric properties of Ag8SnS6 and Ag8SnSe6 semiconductors were examined from first principles calculations and the results are compared with the available experiments. The calculations were carried out with density functional theory and semi-classical Boltzmann transport theory. Lattice constants, bulk modulus, electronic band structures, total and partial density of states and thermoelectric coefficients were calculated without using any parameters from the experiments. The predicted ZT are compatible with the existing n-type doped experiments and it was found that the ZT values can be much higher when p-type doping was performed.
- Published
- 2019
49. Kristal yapısı AuCu3 (L12) olan XY3 (X=Eu, Yb; Y=Pb, Pd) bileşiklerinin yapısal, elektronik, fonon ve termodinamik özelliklerinin AB initio hesaplamaları ile incelenmesi
- Author
-
Bürhan, Tuğba, Çoban, Cansu, Fizik Anabilim Dalı, and Fen Bilimleri Enstitüsü
- Subjects
Electronic Properties ,Thermodynamic Properties ,Fizik ve Fizik Mühendisliği ,Phonon Properties ,Ab-initio Hesaplamaları ,AuCu3 Yapı ,Elektronik Özellikler ,Fonon Özellikleri ,Yoğunluk Fonksiyonel Teorisi ,Ab-initio Calculations ,Elastic Properties ,Termodinamik Özellikler ,Physics and Physics Engineering ,Elastik Özellikler ,AuCu3 Structure ,Density Functional Theory - Abstract
Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Fizik Ana Bilim Dalı, AuCu3 (L12) yapıda kristalize olan XY3(X=Eu, Yb, Y=Pb, Pd) bileşiklerinin yapısal, elektronik, elastik, fonon ve termodinamik özellikleri ab-initio hesaplamalar yapılarak araştırılmıştır. Örgü sabiti, bulk modülü ve onun basınca göre birinci türevi, elektronik bant yapısı ve durum yoğunluğu (DOS), elastik sabitler, Zener anizotropi faktörü, Young ve izotropik makaslama modülleri, Poisson oranı, fonon frekansları ve fonon DOS, termodinamik parametreler hesaplanmıştır. Hesaplanan örgü sabitlerinin literatürdeki verilerle uyumlu olduğu belirlenmiştir. Elastik sabitlerin kararlılık kriterlerine uyduğu ve 0-40 GPa basınç aralığında artan basınçla arttığı görülmüştür. Ayrıca Debye sıcaklığı, boyuna, enine ve ortalama ses hızları da elastik sabitler kullanılarak hesaplanmıştır. Bant yapısı grafiğinde bant aralığına rastlanmadığından bileşiklerin metalik karakterde olduğu tespit edilmiştir. Termodinamik özelliklerden entropinin sıcaklıkla arttığı, ısı kapasitesinin de yüksek sıcaklıklarda Dulong-Petit limite yaklaştığı görülmüştür. Elde edilen fonon dağılım eğrisi ve fonon DOS değerleri incelendiğinde bileşiğin dinamik kararlı olduğu sonucuna varılmıştır., The structural, electronic, elastic, phonon, and thermodynamic properties of XY3 (X=Eu, Yb; Y=Pb, Pd) compounds crystallized in AuCu3 (L12) structure were investigated by performing ab-initio calculations. Lattice constant, bulk modulus and its first pressure derivative, electronic band structure and density of state (DOS), elastic constants, Zener anisotropy factor, Young's and isotropic shear moduli, Poisson's ratio, phonon frequencies and phonon DOS, thermodynamic parameters were calculated. The calculated lattice constants were determined to be consistent with the data in literature. It has been observed that the elastic constants met the stability criteria and increased with increasing pressure in the pressure range of 0-40 GPa. Besides, Debye temperature, longitudinal, transverse, and average sound velocities were calculated from elastic constants. Since, no band gap was not observed in the band structure graph the compounds were found to be metallic character. It was seen that thermodynamic properties of the entropy increased with temperature, heat capacity approached Dulong-Petit limit at high temperatures. When the obtained phonon distribution curve and DOS values were examined, it was concluded that the compound was dynamically stable.
- Published
- 2019
50. Determınatıon of some dıvalent metal complexes by molecular sımulatıon method
- Author
-
Özgür Fıçıcı, Sejda, Okan, Şevket Erol, and Fen Bilimleri Enstitüsü
- Subjects
Transition Metal Complexes ,Molecular Simulation ,Moleküler Benzetim ,Geçiş Metali Kompleksleri ,Yoğunluk Fonksiyonel Teorisi ,Çözeltilerde İyonik Koordinasyon ,İonic Coordination İn Solutions ,Density Functional Theory - Abstract
Geçiş elementleri olan nikel ve bakırın hidrojen bağlı sıvılar, su, etilen glikol ve gliseroldeki koordinasyonları yoğunluk fonksiyonel teorisi hesaplamalarıyla elde edildi. Sonuçlar aynı metal kompleksleri için elde edilen nötron difraksiyonu sonuçlarıyla karşılaştırıldı. Nikel-su ve bakır su kompleksleri için deneyle uyumlu sonuçlar elde edildi. Ayrıca bakır-su kompleksi için ilk kabuğu kapsayacak daha uzun menzilli çift dağılım değerleri elde edildi. Nikel- ve Bakır etilen glikol ile ilgili olarak, yüksek k değerlerinde istatistiksel hatalar nedeniyle ikinci koordinasyon kabuğunun aydınlatılamadığı nötron kırınım deneylerinin teorik olarak sağlanabileceği gösterildi. Nikel-gliserol kompleksi için kısa menzilde deneyle uyumlu sonuçlar elde edildi. Bunlara ek olarak uzun menzilde kaldığı için nötron difraksiyonuyla ulaşılamayan bir bilgi olarak etilen glikolün ilk ve ikinci koordinasyon kabuğundaki geometrik düzenlemesi elde edildi. The coordination environment of the transition elements of nickel and copper in hydrogen bonded liquids such as water, ethylene glycol and glycerol are calculated by density functional theory methods. The results were compared with the neutron diffraction findings for the same metal complexes. The theoretical results for nickel-water and copper water complexes are in good agreement with that of experimental results in the neutron diffraction. A longer ranged pair distribution distances from copper ion can be determined covering the first coordination shell by the calculations in comparison with those of the experiment. With respect to nickel- and copper- ethylene glycol, it is established that the second coordination shells, which cannot be illuminated due to statistical errors at high-k values in neutron diffraction, are approachable by density functional theory simulations. For the nickel-glycerol complex, the short-range experimental results were obtained by the calculations. In addition, the geometric arrangements of the ethylene glycol in the first and second coordination shells were obtained as information which could not be reached by neutron diffraction as it remained in the long range.
- Published
- 2019
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