Search

Imidazole is an organic colorless compound having chemical formula C3H4N2. It produces a slightly alkaline solution when dissolved in water. Imidazole is included in many biological molecules. The fundamental one is amino acid histidine which contains an amino group, a carboxylic acid group and a positively charged imidazole functional group. Histidine plays an important role in structure and binding functions of hemoglobin. Consequently, to investigate its proton transfer property becomes essential. In this study proton transfer from imidazole to chloranil is studied by Density Functional Theory (DFT). [ABSTRACT FROM AUTHOR]

This study is about the FP-LAPW (Full Potential Linearized Augmented Plane Wave) method used for density functional theory (DFT) to study the structural phase transition of PbTe under pressure. Our results indicate that a structural transformation from NaCl to CsCl occurs at 13.9 GPa, which is in good compatibility with search observations. To determine the soil condition properties of the B1 crystalline structure, the total energy was found to be FUNCTION OF THE UNIT CELL VOLUME. The PBA-GGA exchange-correlation potential was utilized to evaluate the density of states, electronic band structure, and optical spectra. Novelty is we theoretically determined the second-order elastic constants, as well as thermo-mechanical properties of PbTe. Our computed results are in line with available theoretical and experimental data. [ABSTRACT FROM AUTHOR]

Electronic and thermal properties of rare-earth chalcogenide compounds R2X3 (R = Dy/Tb and X = S/Se) are investigated using Density Functional Theory. The effective mass, deformation potential and elastic constants are calculated. The rare-earth chalcogenide compounds are dynamically stable. The lattice thermal conductivity for these compounds is calculated using slack model. The lowest value of kl 4.5W/mK is obtained for Tb2Se3 This low thermal conductivity of these compounds can have several application in various fields like thermoelectric, thermal insulation and phononics. [ABSTRACT FROM AUTHOR]

Using density functional theory (DFT) structural, electronics characteristics and stability of half-Heusler PdTiSn compounds have been reported at various values of tensile strain. The calculated phonon dispersion curves, confirm the thermodynamic stability of PdTiSn material at 10% amounts of isotropic strain. Calculations show that when different values of tensile strain are applied, the energy bandgap varies dramatically. The value of the band gap is changed from 0.79eV to 0.45eV and the nature of the material is retained to be indirect band gap semiconductor. The estimated outcomes reveal that PdTiSn material may be used for thermoelectric applications. [ABSTRACT FROM AUTHOR]

In this research, we looked at the quantum capacitance and electronic structure of WS2 monolayers that had undergone chemical modification. Different ad-atom adsorption techniques have been used to functionalize these monolayers. Density functional theory has been used in calculations to precisely determine the electrical structure of a monolayer of ad-atom doped WS2. We have calculated All functionalized systems have a quantum capacitance. The quantum capacitance of every functionalized system was then calculated. Above 1000 μF/cm2, a noticeable quantum capacitance has been seen. Our calculations demonstrate that substitutional doping utilising various ad-atoms raises the quantum capacitance of these monolayers significantly. The microscopic cause of this system's increased quantum capacitance has been investigated. The system has a very large quantum capacitance as a result of the formation of new electronic states close to the band edge and the shift in the Fermi level brought on by the ad-atom adsorption, according to our DFT-based calculation. [ABSTRACT FROM AUTHOR]

Malaria control remains a challenge, especially in countries where a large population lives in poverty. Conventionally, quinolines like quinine, chloroquine, and mefloquine have been used for treating malaria for many years. However, Plasmodium falciparum, the Malaria parasite widely prevalent in African countries, reportedly resisted CQ. Reportedly, the K76T mutation in the pfcrt gene (plasmodium falciparum chloroquine resistance transporter) has been responsible for CQ-related resistance. Studies suggest that the mutated protein product of the gene allows the chloroquine to escape from the vacuole in an energy-independent process, causing resistance. Because lactate dehydrogenase (LDH) plays a vital role in the carbohydrate metabolism in plasmodium, it can be considered a suitable target for drug design strategies. In the current study, a series of chloroquine derivatives, namely, Hydroxychloroquine-o-acetate (compound 1), 4-((7-chloroquinoline-4-amino) penta-1-ol (compound 2), Bis-desethylchloroquine (compound 3) were selected for preliminary investigation as anti-plasmodial drugs. The optimized geometry corresponding to the global minimum energy was predicted using density functional theory and Gaussian 03 software. The optimized geometries were then subjected to molecular docking studies against Pf-LDH using CHIMERA software to assess their suitability as anti-plasmodial agents. The bioavailability of these compounds was evaluated by computationally assessing features such as absorption, distribution, metabolism, extraction, and toxicity. Insights into the drug-likeness of the select compounds were also analyzed by computing physiochemical parameters like topological polar surface area, lipophilicity, blood-brain barrier, etc. [ABSTRACT FROM AUTHOR]

In this work, we investigated the quantum capacitance and electronic structure of WSe2 monolayers that have undergonechemical modification. Various methods of ad-atom adsorption have been employed to functionalize these monolayers. Density functional theory calculations were performed in order to precisely determine the electrical structure of a monolayer of ad-atom doped WSe2. Each functionalized system's quantum capacitance was then estimated. A noticeable quantum capacitance has beenobserved over 1000 µF/cm2. Based on substitutional doping with different ad-atoms, our calculations demonstrate a significant enhancement of these monolayers' quantum capacitance. There has been research done on the microscopic reason for the enhanced quantum capacitance of this system. Due to the ad-atom adsorption-induced change in the Fermi level and the creation of new electronic states close to the band edge, our DFT-based calculation reveals that the system has a very large quantum capacitance. [ABSTRACT FROM AUTHOR]

Application of nanoparticles in biomedicine has shown enormous impact in enhancing the drug efficiency, localized treatment, minimum side effects, etc. Among the diverse range of nanoparticles, organic nanoparticles pose a great deal of superiority owing to their smaller size, biocompatibility, and improved solubility. Quest for new small organic molecule-based nanoparticles is the need of the hour in order to avoid lengthy and critical synthesis of other organic nanoparticles viz. polymer nanoparticles, lysosomes, etc. In the present report, we have studied important photophysical properties of naphthalene-based organic nanoparticles, which indicated their improved fluorescence lifetime useful for easy accumulation in the biological systems. The intriguing spectral properties are also supported by density functional theory (DFT) calculations. A systematic investigation from naphthalene molecule to an infinite array of stacked naphthalene units shows increased absorption at around ∼300 nm. In the case of naphthalene nanoparticles, the absorption wavelength is found to be independent of the nature and extent of aggregation. The present article also establishes the significance of the nanoparticles formed from the otherwise hydrophobic polynuclear aromatic hydrocarbons in the field of drug delivery. [ABSTRACT FROM AUTHOR]

In the present investigation we performed density functional theory (DFT) calculations to study adsorption and binding energies, density of states (DOS) for pristine graphene, Hafnium (Hf) decorated graphene and hydrogen molecule (1H2−6H2) adsorbed on Hf-decorated graphene as well. We found adsorption energy in negative range -221.524 Ry for pristine graphene, after decorating Hf atom adsorption energy found -345.891 Ry. When we successively increase the hydrogen molecules (1H2−6H2) the adsorption energy decreases gradually, it ranging from (-348.197 Ry to -358.99 Ry). The binding energy per H2 molecule also decreases from 2.306 to 0.377 eV. The evaluated Fermi energies of studied system found in the range 1.089 eV to 3.928 eV. The successive increase in Fermi energy confirms the hydrogen molecules (1H2-6H2) have sufficient surface area of Hf decorated graphene. Our investigation reveals that Hf decorated graphene could be a promising material to store H2 molecules on a Hafnium (Hf) decorated graphene system. [ABSTRACT FROM AUTHOR]

The study of curcumin degradation has been carried out by optimizing the effect of pH and solvents using the UV-Vis spectrophotometric method. The stability of curcumin decreased as pH increased. Curcumin was degraded rapidly in alkaline solutions. Curcumin has different maximum wavelengths in the different solvents. The UV spectrum of curcumin shifted as the pH increased. The UV spectra of curcumin shifted towards a smaller wavelength in alkaline solution. The shift in the UV spectra was due to curcumin degradation in an alkaline solution. In addition, Density functional Theory (DFT) calculation was carried out to simulate the curcumin and its degradation product ground states and excited states. The absorption spectra calculated using the TDDFT method showed that the maximum wavelength of curcumin and its degradation products agreed with the experimental data. [ABSTRACT FROM AUTHOR]

We introduced the Coulomb repulsion to carry out non-collinear density functional theory to explore the thermal electric conductivity in the in-plane ferromagnetic single layer NiCl2. The calculations included the temperature near the critical temperature of NiCl2 and room temperature. The Boltzmann transport approach was applied to calculate thermal electric conductivity after reaching self-consistent calculations. We found zero thermal electric conductivity in the Fermi level for all values of Coulomb repulsions, leading to the insulating state. However, inserting the doping can obtain the metallic state. While electron doping can be applied for the slight Coulomb repulsion, hole doping should be applied for the significant Coulomb repulsion. [ABSTRACT FROM AUTHOR]

We introduced the Coulomb repulsion to carry out non-collinear density functional theory to explore the thermal electric conductivity in the in-plane ferromagnetic single layer NiCl2. The calculations included the temperature near the critical temperature of NiCl2 and room temperature. The Boltzmann transport approach was applied to calculate thermal electric conductivity after reaching self-consistent calculations. We found zero thermal electric conductivity in the Fermi level for all values of Coulomb repulsions, leading to the insulating state. However, inserting the doping can obtain the metallic state. While electron doping can be applied for the slight Coulomb repulsion, hole doping should be applied for the significant Coulomb repulsion. [ABSTRACT FROM AUTHOR]

In Halogen bonds are crucial to numerous disciplines, including biological systems, drug development, and crystal engineering. (Density functional theory) was used in this study to examine the structural properties of the halogen bonds (Cl, Br, and I) and benzene. Geometry optimization, infrared spectra, and some electronic properties have been achieved. All computations were based on the density functional theory (DFT) at the 6-31G (p, d) basis set B3LYP level throughout the Gaussian 09 package. The electronic properties are represented by the ultraviolet spectrum, HOMO and LUMO energies, the visible spectrum, and bond length. The structural properties are represented by the nuclear magnetic resonance (NMR) spectrum, the intrinsic reaction coordinates (IRC), and the benzene ring. The exterior vibrations of the theoretically formed benzene rings are anticipated to be either active in the infrared or Raman spectrum due to the high degree of symmetry of their constituent elements. The molecule's active bands are in the mid-infrared for fundamental and combination bands, which are the only ones visible in the spectrum. However, due to its symmetry, no overtone bands were found in this region. The ultraviolet region begins to appear at 224 nm due to electronic changes (δ-δ* and π-π*). [ABSTRACT FROM AUTHOR]

Armchair (5, 5) carbon nanotubes doped with germanium atoms (Ge, n = 1-4) were explored theoretically in this work. Density functional theory (DFT) with hybrid functional Becke 3-parameter Lee–Yang–Parr (B3LYP) and a basis set 6-31G* were used to investigate the structural and electronic properties of the resulting nanotubes. The stability of the substitutional Ge atoms was thus studied and explained in terms of the binding energy per dopant atom. The density of state and HOMO-LUMO gap showed that electrical conductivity increases gradually with the number of dopants. The ionization potential, electron affinity, chemical hardness and softness, and chemical potential were also calculated. [ABSTRACT FROM AUTHOR]

We reported our preliminary results in our study of electronic band gap engineering of Graphene Quantum Dot by calculate the electronic properties of the bulk properties by means graphene. The calculation was done by density functional theory as implemented in quantum espresso (QE). The results showed that the graphene is the gapless semiconductor with fermi energy 5.223 eV. When the size of the graphene decreases until <10 nm, its band gap is tunable by vary its size. The challenge in this study is how we tune the gap as function of size of graphene which need the large supercell. The effect of the supercell's size on band gap will be reported in another publication. [ABSTRACT FROM AUTHOR]

The present study uses density functional theory (DFT) and non-equilibrium Green's function (NEGF) to investigate the transmission coefficient T (E) for dithino-naphtridine molecules with different positions of side group oxygen atoms. The electric conductance calculation shows that the bare molecule has a higher conductance than the molecules with oxygen dangling, which varied from-4.7 to-5.5(eV), while the Seebeck coefficient (S) is found for all molecules with a positive sign with a higher value of 254 (µV/K) for molecules terminated by hydrogen around Fermi level EF = 0. Other thermal parameters are calculated, such as thermal conductance K which is found to change between 55 x10−15 for M_1and 4x10−15 (w/K.m) for M_3. Finally, the higher value of the figure of merit (ZT) is about 0.8 for molecule M_3. [ABSTRACT FROM AUTHOR]

The Gaussian 09 software program is used with ab-initio Density Functional Theory (DFT), according to generalized gradient approximation (GGA) of the B3LYP with 6-311G** basis set are used to calculate the electronic and vibrational properties of MgO wurtziods structured at the molecular scale (molecule, cyclohexane), while at Nano-scale included (wurtzoid, wurtzoid2c and triwurtzoid) capped bundle (3,0) nanotube. The electronic properties included density of state, energy gap, and density of bond length, while vibrational properties included infra-red and Raman spectra, reduced masses, force constant as well as longitudinal optical modes were investigated. The Gauss view 05 programs are used to study the geometrical visualization of MgO at molecules and wurtzoids nanostructure. The values of the energy gap of MgO at wurtzoids nanostructure (wurtzoid, wurtzoid2c and triwurtzoid) are as follow (3.9668, 3.66 and 3.44 eV) respectively, these values agree with theoretical values of MgO bulk (4.2 eV) and compared with the experimental value of MgO wurtzite (7.8 eV). The studied vibrational included Raman and IR spectra, force constant, reduce masses, as a function of frequencies and longitudinal optical modes which was around (692 to 720 cm−1) and agreed with experimental results of longitudinal optical of MgO bulk. [ABSTRACT FROM AUTHOR]

For spintronics applications, the materials which have high spin-polarization at the Fermi level are prospective materials. In this study, we investigated how spin-orbit coupling affected the electronic and magnetic characteristics of Mn1.5PtSn, an inverse tetragonal Heusler compound exhibiting both ferromagnetic and ferrimagnetic spin orders. By employing density functional theory calculations, we determined that at the ground state the ferrimagnetic configuration is more stable than the ferromagnetic one, in spite of the spin-orbit coupling. To validate our findings, we analyzed the density of states and band structure plots for the compound. Our results suggest that precise modification of the constituent atoms could transform this compound into a half-metallic material appropriate for spin-transfer-torque-based technology. [ABSTRACT FROM AUTHOR]

Two dimensional (2D) van der waals (vdW) Janus heterostructures are the smart artificial materials with unique phys-ical, chemical, and quantum properties. Here, the electronic and optical properties of 2D Janus MoSeTe/WSeTe heterostructures are investigated systematically at different rotation angles by density functional theory. Four rotation angles were chosen in be-tween 0 - 600 by considering the fact that the lattice mismatch between the monolayers will be minimum. The relative rotation between the monolayers provide an extra degree of freedom to enable various fascinating phenomena in the heterostructure. The phonon dispersion and adhesion energy confirms the Janus monolayers and its heterostructures were found to be dynamically and thermodymically stable respectively. The bandgap of the heterostructure reduces as compared to its monolayer and lie in the range between 0.4 - 0.6 eV for all considered rotation angles. It is interesting to note that the MoSeTe/WSeTe heterostructure possess a type-II band alignment, which is a crusial parameter for separation of carriers. In addition to this, the heterostructure is opti-cally active in visible to infrared region with a high value of absorption coefficient for θ = 00. These results show the potential applications of 2D Janus heterostructures in nonoelectronics, spintronics, and optoelectronic devices. [ABSTRACT FROM AUTHOR]

In reference to the first principle Density Functional Theory (DFT) using the Generalized gradient approximation and Perdew-Burke-Emzerhoff scheme, the structural, electronic, mechanical and optical properties of bismuth ferrite ceramics are studied. The optimized lattice parameter function of the hexagonal structure, the band structure, density of states, optical properties, independent elastic constants, that is young's, bulk and rigidity modulus and Poisson ratio are calculated using CASTEP module. [ABSTRACT FROM AUTHOR]

In this paper, we report the systematic study of formation energy, electronic, and magnetic properties of Iron-doped Hydrogen-saturated Silicon Nanowire (Fe:H-SiNW) using the first principle density functional theory. The results were obtained by the generalized gradient approximation (GGA) approach and examined along (100) direction-oriented silicon nanowire with a diameter of 1nm. The results showed that H-SiNW is a nonmagnetic semiconductor, while Fe:H-SiNW is a ferromagnetic half-metal. This study revealed that H-SiNW doped by Fe impurity can form a new type of 100% spin-polarized material, which is potentially fascinating for nano-electronic and nano-spintronic devices. [ABSTRACT FROM AUTHOR]

Using the density functional theory technique, the chemical compound 2-(tert-Butylamino)-1-[4-hydroxy-3-(hydroxymethyl)phenyl]ethanol was investigated for use as a corrosion inhibitor. By using the commonly used harmful corrosion inhibitors, the toxicity has increased. Due to strict environmental regulations regarding the usage and disposal, there is a concern in replacing the hazardous corrosion inhibitors with effective non toxic inhibitors. The organic compounds can be used as a corrosion inhibitors as it becomes a popular and cost - effective approach of preventing corrosion in metals. In order to ascertain how potential corrosion inhibitors may act, quantum chemical parameters including EHOMO, ELUMO, Energy gap (Δ E), dipole moment (µ), electron affinity (A), ionisation potential (I), absolute electronegativity (χ), global hardness (η), softness (S), and electrophilicity index (ω), are determined with B3LYP / 6 - 311++ G(d,p) level. UV-Visible spectrum studies has also been computed employing TD– DFT method. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT), ab initio, and Monte Carlo simulations have been used to study the corrosion inhibition of copper by the monoterpenoids menthol, isopulegol, terpinen-4-ol, and α-terpineol. Quantum chemical parameters to provide information about the electronic properties of the tested molecule as a corrosion inhibitor. Monte Carlo simulations present target molecules' dynamics and inhibition mechanisms on copper surfaces. Quantum parameters and adsorption energy results show that α-terpeneol has the potential to have the highest corrosion inhibition efficiency. [ABSTRACT FROM AUTHOR]

Non-Faradaic electrochemical modification of catalytic activity (NEMCA) with an electric field (EF) has attracted attention as one of the methods to improve catalyst performance. However, this activation mechanism is not still clear. In this study, we focused on the NEMCA mechanism in CO2 methanation on Ni metal catalyst with solid oxide electrolysis cell (SOEC) and calculated two possible effects of the NEMCA mechanism; direct EF applications and oxygen atom co-adsorptions, using the density functional theory calculations and detailed kinetic simulations. Compared with these effects in terms of kinetic energy changes in the rate-determining steps, it has been revealed that the spillover effect of lattice oxygen toward the catalyst surface is dominant in the NEMCA mechanism. Also, we have found that overall CO2 methanation is promoted in SOEC mode with oxygen atom co-adsorptions in both cases of Ni flat and step sites. [ABSTRACT FROM AUTHOR]

The utilization of non-renewable energy source is expanding quickly which brings about a rising global warming and other ecological issues. To dispose of this perilous circumstance, the analysts put forth attempts to foster innovations that depend on inexhaustible sources. First principle computations of structural, band structure and optical properties of CdZnS2 semiconductors are concentrated in the current paper inside the system of density functional theory (DFT) and Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA) encapsulated in Wien2k code. The full potential linearized augmented plane wave method (FP-LAPW) method is used for solving the basis sets. The band structure and density of states (DOS) are registered for that yield 1.37 eV band gap of this compound. The integrated absorption coefficient is 77.976 5548 (×104 eV/cm) is computed by the absorption spectra. All the electronic and optical properties prove that this compound is reasonable for photovoltaic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

Plain and hybrid density functional theory (DFT) under the umbrella of linear combination of atomic orbital have been engaged to report energy bands, density of states (DOS), Mulliken population (MP) and Compton profile (CPs) for Al2O3. Plain DFT computations were accomplished under the scheme of local density approximation and generalized gradient approximation whereas the standard PBESOL0 and HSE06 approximations were consider for the hybrid category. Theoretical CPs have been validated with CP measurements using 100 mCi 241Am (point source) Compton spectrometer and HSE06 was found to be in better accordance with the experimental CP. Further, energy bands and DOS have settled the insulating nature while MP analysis suggests the ionic character dominance in the Al2O3. [ABSTRACT FROM AUTHOR]

Plain and hybrid density functional theory (DFT) under the umbrella of linear combination of atomic orbital have been engaged to report energy bands, density of states (DOS), Mulliken population (MP) and Compton profile (CPs) for Al2O3. Plain DFT computations were accomplished under the scheme of local density approximation and generalized gradient approximation whereas the standard PBESOL0 and HSE06 approximations were consider for the hybrid category. Theoretical CPs have been validated with CP measurements using 100 mCi 241Am (point source) Compton spectrometer and HSE06 was found to be in better accordance with the experimental CP. Further, energy bands and DOS have settled the insulating nature while MP analysis suggests the ionic character dominance in the Al2O3. [ABSTRACT FROM AUTHOR]

For practical use, interactions of biomolecules with nanomaterials play crucial role to design new material in wide range of applications. The physical adsorption mechanism of Alanine (Ala) molecules on surface of pristine semiconducting, zigzag single walled carbon nanotubes (8,0) (SWNTs) were quantum chemically computed by applying density functional theory (DFT). Thermodynamical extracted data indicates favorable binding of L-alanine-SWNT complex system and it depends on orientation of L-alanine molecules i.e., weak binding is observed. We calculated various parameters including adsorption energy, density of states (DOS) and HOMO-LUMO gap on surface of SWNT (8,0), it absorbs amino acids L-alanine with release of energy owing to its CH3, -COOH and -NH2 functional groups. There are no bonded interactions between Ala-SWNT (8,0) biomolecular complex system. Our results are useful for targeted drug delivery of L-Alanine in biomedical applications, besides to this, the biosensors[1] can be used to check concentration level of alanine in patients to avoid delay in treatment as well. [ABSTRACT FROM AUTHOR]

In the present work, we have studied the impact of compressive and tensile strain on the janus monolayer PtSeTe via the first principle calculations based on density functional theory. It is found that the unstrained janus monolayer has a hexagonal unit cell with positive phonon frequencies. On the application of compressive strain, the janus monolayer PtSeTe has a metallic nature whereas for the tensile strain it shows the transition from indirect band gap semiconductor to direct band gap semiconductor. We have also computed the real and imaginary parts of Janus monolayer PtSeTe. From the obtained results we conclude that janus monolayer PtSeTe is a highly strain-sensitive material and could be tuned for various optoelectronic devices and its application. [ABSTRACT FROM AUTHOR]

Using density functional theory, the effect of layer number and stacking pattern on the electronic and optical properties of PdSe2 is explored. The size of the band gap and optical properties are very sensitive to the stacking pattern. The monolayer PdSe2 (m-PdSe2) has band gap of about 1.29 eV and its value drops with rise in layer thickness. The band gap of bilayer PdSe2 (b-PdSe2) changes from 1.13 eV to 0.79 eV with stacking pattern AA and AB, respectively. The optical properties like dielectric function, absorption coefficient etc. are also calculated. The bilayer PdSe2 with stacking AB is found to have the most prominent optical properties. A red shift in optical properties is also observed as the number of layers increases. [ABSTRACT FROM AUTHOR]

We report the spin-orbit coupling (SOC) induced electronic, optical and electronic transport properties of Janus BiTeI monolayer using density functional theory and semi-classical Boltzmann's transport theory. The calculated indirect bandgap value for BiTeI monolayer using SOC level of theory is 0.61 eV. The in-plane optical absorption peak for the BiTeI monolayer is calculated at 2.33 eV. The calculated maximum value of power factor (PF) for BiTeI lies in the range of 151-235 V2/K2Ωms within a temperature range of 300K-700K. The high value of power factor and strong absorption ability with a finite value of bandgap indicates that BiTeI monolayer is a promising candidate for thermoelectric and optoelectronic application. [ABSTRACT FROM AUTHOR]

We investigate detailed electronic structure properties of various iron-based superconducting compounds. Density functional theory (DFT) based first principles calculations are performed. Lifshitz like electronic topological transition is predicted in a variety of Fe-based superconductors. With doping, an interconnection between Lifshitz like electronic topological transition and superconductivity is found. We predict from first principles calculations that the Lifshitz transition occurs at the same doping level at which the highest Tc is reported in literature for these iron-based superconductors. These findings indicate an universal interconnection between the electronic Lifshitz transition and superconductivity in these high-Tc compounds. Specific examples of interconnection between the electronic topological transition (ETT) which occurs in Fermi surface of 122 superconducting Fe-based compounds with doping are demonstrated. [ABSTRACT FROM AUTHOR]

Excitonic effects in semiconductors play a vital role in optoelectronic devices, such as solar cells and light emitting diodes. We performed the relationship between the band structure and exciton binding energy using first principle calculation based on Density Functional Theory (DFT) within PBE-GGA exchange correlation potential for Lithium nitridorhenate (Li5ReN4). We also estimated charge density, effective mass, and electronic band structure. According to our calculations, Li5ReN4 possesses a direct band semiconductor with a band gap of 2.68 eV. Our approach may be used to comprehend the excitonic phenomena in semiconductor materials. [ABSTRACT FROM AUTHOR]

The Full Potential Linearized Augmented Plane Wave (FP-LAPW) method that relied on density functional theory (DFT) was employed to examine the structural, electrical, and transport properties of K2SnBr6 compound. For structural optimization Generalized gradient approximation (GGA) was considered while mBJ potential was addressed for electronic band structure estimation. The computed band structure for K2SnBr6 is 2.23 eV. The transport parameters such as See beck coefficient, thermal conductivity, electrical conductivity, and power factor as a function of temperature as well as chemical potential were calculated using the Boltzmann transport equations. Thehighpower factor of the investigated cubic K2SnBr6 compound suggest its potential application in thermoelectric devices. [ABSTRACT FROM AUTHOR]

The study of structural, electronic, and thermal properties of two dimensional NbSe2 monolayer is performed using density functional theory (DFT). The binding energy and phonon spectra are calculated to ensure the structural and thermal stability of the monolayer. Moreover, the free energy, is decreases with the temperature while the entropy and specific heat increases. The reason of metallic character of NbSe2 ML is discussed. Furthermore, the stress-strain relationship is studied to calculate the tensile strength. The uniaxial strain deviate the C3v point group symmetry which leads to induced half metallic nature of monolayer manifests its important application in the field of futuristic spintronics. [ABSTRACT FROM AUTHOR]

We report the structural and magnetic properties along with the electronic structure of ordered double perovskites La2MIrO6 (M = Mg, Zn). An antiferromagnetic ordering below TN ∼ 12 K and weak ferromagnetic ordering below Tc ∼ 9 K is observed in La2MgIrO6 and La2ZnIrO6, respectively. A small hysteresis loop along with non-saturating magnetization even at large magnetic field suggests a canted-antiferromagnetic ground state in La2ZnIrO6. The valence band photoemission spectra at room temperature exhibit zero intensity at the Fermi level (EF), while density functional theory (DFT) calculation within local density approximation (LDA) suggests a metallic ground state. A rigid shift was observed in the O 2p band position in the experimental spectra compared to LDA results. These results suggest the importance of electron correlation in the ground state properties of these systems. [ABSTRACT FROM AUTHOR]

All inorganic halide perovskites have received tremendous significance in the perovskite solar cells (PSCs) technology. The toxicity in PSCs due to Pb element concerns to the environment, thus replacement of Pb is a prerequisite in the development of PSCs. In this study, we have studied strain-induced structural and electronic properties of lead-free ASnBr3 (A = Cs, Rb, K) perovskites using density functional theory based first principles calculation. The band gap values of these perovskites are varied from 0 to 1.14 eV within the strain range of -4 to 4%. [ABSTRACT FROM AUTHOR]

We performed ab-initio calculations based on density functional theory (DFT) for obtaining the generalized stacking fault energies (GSFEs) and elastic moduli of Cu, magnetic and non-magnetic Ni and Ni0.5Cu0.5 alloy. We have studied the effect of magnetism on the elastic constants and GSFEs in 50% Cu doped Ni alloy. The GSFEs and elastic constants show a decrease upon Cu doping in agreement with the trends in theoretical and experimental results for Ni-rich alloy of Ni-Cu. The Rice criteria [1] analysis showed that adding Cu to Ni reduces the ductility of Ni which may lead to an increase in the strength of alloy compared to pure Cu and Ni. [ABSTRACT FROM AUTHOR]

We use first-principles density functional theory (DFT) calculations to obtain solid-solid interface energy of bccTi ( 1 ¯ 12)/hcp Ti(1 1 ¯ 00). We find that the interface energy is negative which accounts for the strong chemical bonding and mixing of atoms in the interfacial region leading to spontaneous phase transformation. The lower interface energy for the hcp Ti/bcc Ti interface than that reported for other fcc Fe/hcp Fe and Ti/TiX(X=C, N) interfaces in the literature gives this interface a much better stability. [ABSTRACT FROM AUTHOR]

A new organic nonlinear optical material 7-(4-bromobenzyl)-3-(tert-butyl)-4H-[1,3,4]thiadiazolo[2,3-c][1,2,4]triazin-4-onehemihydrate (TDTZ) single crystal was grown by slow evaporation solution technique. The lattice parameters of the grown crystal were elucidated by single crystal X-ray diffraction method. The crystal structure revealed the crystallization of the compound in the monoclinic system withthe C2/c space group. UV-Vis NIR spectrum analysis deciphered TDTZ's optical transmittance, cutoff wavelength, and bandgap. Hirshfeld surface studies were performed to understand the intermolecular interactions of the title compound. The density functional theory (DFT) using B3LYP functional with 6-311G (d,p) basis set was carried out forFrontier Molecular Orbital (FMO) analysis to estimate the transition barrier and chemical reactivity. Nonlinear optical activity wasdetermined from TDHF methods with 6-31G(d) basis sets using the GAMESS program. [ABSTRACT FROM AUTHOR]

In the present work, chitosan nanoascorbate Bombyx mori (CSNA) based on high-molecular-weight chitosan (CS) and ascorbic acid (AA) was synthesized by ionotropic gelation in the presence of tripolyphosphate (TPP). The results of the conducted kinetic studies show that in the studied interaction, the order of the reaction of ascorbic acid exceeds the order of the reaction of chitosan. In this study, theoretical studies based on density functional theory (DFT) have performed to comprehend the interaction between of chitosan dimer with AA and sodium tripolyphosphate (TPP) by during the formation of chitosan ascorbate (CSA) nanostructure. Based on existing results, the CS monomer formed of complexes occurs due to the donor-acceptor interaction, which is energetically favorable in all considered inter-actions according to the calculations. The order of values interaction energy de-creases: CS-AA (-68.76 kcal/mol), CS-TPP (-64.58 kcal/mol), which indicates that in the process of formation of CSNA, in most cases, the formation of a donor-acceptor bond occurs between the amino groups of CS with the enol group of AA. The introduction of the aqueous phase led to a drop in the interaction energy. CS nanoparticles can protect ascorbic acid from degradation and improve the stability of AA. [ABSTRACT FROM AUTHOR]

As a precursor to one of the air quality index parameters SO2, understanding the oxidation reaction of sulfur-containing species - dimethyl sulfide (DMS) is important to control the allowable amount of SO2 in the atmosphere. The reaction mechanisms of OH radical with DMS in the presence of one water molecule were then investigated theoretically. The calculations were performed using density functional theory with a dispersion correction. The results showed that the water molecule can form a ternary complex with DMS and OH radical through three different mechanisms, namely DMS − H2O + OH complex, DMS – OH + H2O complex and OH – H2O + DMS complex with an energy barrier at, 14.662 kcal/mol, 22.188 kcal/mol, and 6.073 kcal/mol, respectively. Since OH – H2O + DMS complex displayed the lowest energy barrier, even lower than that of OH radical and DMS (OH – DMS) complex at 11.772 kcal/mol, this suggests that the formation of the ternary complex of OH radical, H2O and DMS (OH – H2O + DMS) is most likely to first occur in the atmosphere. [ABSTRACT FROM AUTHOR]

Clusters of pyrolyzed polyacrylonitrile (pPAN) and metal-containing (Cu, Co, Fe) pyrolyzed pPANs are obtained and investigated using the density functional theory method. The total energies of the clusters were estimated in the Gaussian 09 software package using the 6-31 G and 6-311 G basis sets and the B3LYP functional. In addition, polarizing additions were used in the work. The most stable systems are installed. Within the framework of the density functional theory, the parameters of the interaction of pollutant gases with clusters of pPAN and metal-containing pPAN (Co, Cu, Fe) are calculated. A comparative analysis of the results obtained with the data previously obtained by the method of molecular mechanics is carried out. It was found that the interaction of pollutant gases with clusters of pPAN and Cu- and Fe- containing pPAN is significantly influenced by the O2 molecule, while the interaction with the cluster of Co-containing pPAN is influenced by the H2O molecule. An energy gain was revealed in the interaction of pPAN and metal-containing pPAN clusters with a Cl2 molecule. According to the results, the interaction between the molecules of pollutant gases and clusters of pPAN and metal-containing (Cu, Co, Fe) pyrolyzed pPANs is mainly of the intermolecular type. [ABSTRACT FROM AUTHOR]

Computational quantum mechanics research and organic molecular modeling can provide information about the characteristics of organic compounds and the adsorption mechanism of corrosion inhibitors. Lignin extracts from various plant parts acted as corrosion inhibitors and have reduced the corrosion rate (2.51-15.26%) in steel. The aims of this study were (1) to predict the molecular structure of protonated lignin using density functional theory; (2) predict the reactivity of lignin species and the interfacial adsorption properties of low carbon steels; and (3) investigate the interaction of neutral and protonated lignin compounds with atoms in H2SO4. This study was conducted using computational modelling. including (1) calculation of the molecular structure optimization of monolignol lignin monomers (p-caumaryl-, coniferyl-, and sinapyl alcohol) as neutral and protonated inhibitor species and (2) modeling of corrosion inhibitor molecules adsorbed on the surface of low carbon steel in H2SO4 medium. The predicted result of the protonated structure shows the tendency of the H+ proton to be bound to the O-phenolic and O-methoxy atoms. The interaction of lignin monolignol molecules with the adsorbed sulfate ion result in physisorption interactions. In contrast, the chemisorption interaction of lignin species occurs through the transfer of heteroatom electrons and the heterocyclic π-ring from the inhibitor to the empty d-orbital of Fe in sulfuric acid. The quantum mechanics calculations results show that the p-coumaryl alcohol molecule has the highest inhibition efficiency value of 23.41%. The results of the Monte Carlo (MC) calculation, enthalpy of inhibitor-Fe 19.673 kcal/mol. At the same time, acid-Fe -126.082 kcal/mol shows that the function of acid as an adsorption medium is stronger than ionized Fe. Based on the calculation of DFT/B3LYP 6-31G(d,p) the adsorption of p-coumaryl alcohol in H2SO4 has the highest inhibition efficiency with a bond energy of 78.543 kJ/mol. [ABSTRACT FROM AUTHOR]

In this work, we have analyzed the electronic structure and transmission spectrum of the AA and AB stackedbilayer (2L) MoSe2. The band gap of 2LMoSe2is indirect in nature, with band gap value of AA stacking1.15× times higher than AB stacking. The density functional theory (DFT) calculations in combinations with the non-equilibrium Green's function (NEGF) approach is used to calculate the transmission spectra of 2L-(AA/AB) MoSe2. Further, we comparedthe transmission spectrumof 2L-(AA/AB) MoSe2 along the zigzag (ZZ) and Armchair (AC) orientation using orthorhombic structure of 2L-MoSe2. The results of this analysis will guide researchers in the area of 2L-MoSe2for futuretwo-dimensional (2D) electronic deviceapplications. [ABSTRACT FROM AUTHOR]

The capability of benzo-15-crown-5 ether to form complexes with some heavy metals cation (Cd2+, Hg2+, and Pb2+) has been investigated by the density functional theory method (DFT) using the Gaussian system. The DFT calculations were performed using 6-311G(d,p) with LANL2DZ ECP basis set at the B3LYP level of theory. The interaction energies were used to evaluate the metal binding capability of the crown ethers. The influence of adding substituents was also studied. This calculation showed that the number of ion charge transfers is proportional to the increase of the interaction energy. Furthermore, the existence of the electron donating group (EDG) affected the crown ether's ability to bind heavy metals cation. In addition, based on the extraction interaction energy, charge transfer, and the electron distribution at the HOMO-LUMO orbitals, the selectivity order of derivate 15-crown-5 is Cd2+>Hg2+>Pb2+. [ABSTRACT FROM AUTHOR]

The thermochemical and spectral properties of adenosine phosphate were investigated in this study. To study their ground state and spectroscopic properties, the suggested compounds are designed using the Gauss View 5.0.8 program and then relaxed using the three parameters Lee-Yang-Parr B3LYP hybrid functional density functional theory DFT method with SDD basis sets using the Gaussian 09 package of programs. The Gibbs Free energy, zero-point energies, thermal enthalpies, and thermal energies were investigated. With the addition of phosphorous, the thermal energy, which specifies heat and entropy of the molecule, is enhanced, as for the spectral properties, the IR spectrum of adenosine phosphate compounds was drawn to know the types and number of vibrations, as well as to know the locations of the added groups. [ABSTRACT FROM AUTHOR]

Nitryl cyanide is a promising high-energy-density material containing a strong oxidizer (NO2 group) adjacent to an excellent fuel source (CN group). The structure of the nitryl cyanide crystal at high pressure is predicted using density functional theory (DFT) and evolutionary algorithm. Calculated heat of formation of the trimer (NCNO2)*3, 2,4,6-Trinitro-1,3,5-triazine (TNTA), was determined using GAUSSIAN and interpolation of heats of formation of CHNO compounds as 67.622 kcal/mol for gas phase and 48.1 kcal/mol for solid state. The mass density of the solid was calculated using the total molecular volume method and found to be 1.87 g/cc. The similar, but slightly higher mass density of the predicted crystals were calculated using DFT plane waves (1.85 - 1.97 g/cc, depending on the size of the model). The structure of the nitryl cyanide crystal was found using the molecular option of evolutionary code USPEX by packing up to six NCNO2 molecules. The lowest enthalpy symmetry group of the crystal was found to be P212121, with a density of 3.53 g/cc at 50 GPa, and symmetry P21/c with a density of 3.37 g/cc at 20 GPa. Phonon dispersion calculations indicate the dynamical stability of the new structure like the NCNO2 trimers connected with covalent C-N bonds between the molecules. [ABSTRACT FROM AUTHOR]

A new equation of state for 304L stainless steel has been constructed and entered in the Los Alamos National Laboratory SESAME database with material ID 4273. The equation of state is based on a multiphase approach. The solid and liquid phases were fitted to available experimental data for thermal expansion, heat capacity, and shock Hugoniot, as well as to data from density functional theory calculations of the cold curve and quantum molecular dynamics of the liquid regime. The electronic thermal contribution over the entire equation of state range is based on Tartarus (Green's functions) average atom calculations. For this low-carbon stainless steel both the density functional and electronic thermal calculations are comprised of 19 wt% Cr, 10 wt% Ni, and the remainder Fe. [ABSTRACT FROM AUTHOR]

We present Davis reactant and product equations of state (EOS) for the HMX-based explosive, PBX 9012. We utilize experimental, density functional theory (DFT), and thermochemical data in the calibration, and we emphasize the results of an uncertainty-quantification study of the EOS parameters and resulting EOS quantities (P, V, etc). [ABSTRACT FROM AUTHOR]