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A computational study for reaction mechanism of 1-vinyl 5-hexenyl radicals is carried out using the density functional theory. The results showed that the reaction for the formation of thermodynamically stable 6-endo-trig cyclization product can progress over both 6-endo-trig and 5-exo-trig cyclization. Moreover, our computations demonstrated that when 5-exo-trig cyclization intermediate is stable, 5-exo-trig cyclization mode would be responsible for the formation of the 6-endo-trig cyclization product. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

In this study, we have developed a new approach to investigate the ground state properties of many particle boson systems. Within this approach one can obtain the natural orbitals, which are very useful in describing the properties of many body systems and the filling factors of these orbitals. The method was applied to determine the properties of a many boson system trapped in an isotropic harmonical trap. Calculations were performed for systems containing 10 to 2000 particles in the trap and with s-wave scatttering length changing in the range a 0 - 64aRb. The results were compared with the results obtained from the literature. [ABSTRACT FROM AUTHOR]