نتایج جستجو برای: density functional theory dft
تعداد نتایج: 1668215 فیلتر نتایج به سال:
In this research of cis, trans and vinyl monomeric derivatives of 1,4-butadiene were studied using C20 in different temperatures by Functional density theory (DFT). To this purpose, the materials were firstly optimized geometrically, then the calculations of the thermodynamic parameters were performed on all of them. In the following, changes in parameters of energy...
Electronic properties of CaTiO3 crystal in paraelectric and ferroelectric phases have been studied by first principles, using Hohenberg-Kohn-Sham density functional theory (DFT). In paraelectric phase the results show an indirect band gap of about 2eV at -R direction in the Brilluoin zone and a strong hybridization between Ti-3d an O-2P orbital. In ferroelectric phase a direct band gap of abo...
The structural and electronic properties of C24-2nBn Nn and M@ C24-2nBn Nn (M= alkaline and earth alkaline metals; n=3 and 6) molecules are studied using the Density Functional Theory (DFT). It was found that the most interaction is in M@ C24-2nBn Nn complexes (M=Be, Mg; n=3 and 6). The negative nucleus-independent chemical shifts confirm that C24-2nBn Nn (n=3 and 6) cages exhibit aromatic char...
In the context of the density functional theory we consider the single particle ex-citation spectra of electron systems. As a result, we have related the single particle excitations with the eigenvalues of the corresponding Kohn-Sham equations. In a case when the exchange correlation functional is approximated by the exchange functional the coupling equations are very simple, while the single p...
in this paper, we used quantum chemical approach to shed light on the catalytic mechanism of γ-carbonic anhydrase (γ-ca) to convert carbon dioxide to bicarbonate ion. density functional theory (dft) using b3lyp and ub3lyp functional and three split-valance including 6-31g*, 6-311g** and 6-311++g** basis sets were used to calculate the details of electronic structure and electronic energy of act...
density functional theory (dft) calculations have been performed to investigating the effects of themolecular oxygen impurity on the quadrupole coupling constant (qcc) parameters of armchair and zigzagboron nitride nanotubes (bnnts). optimization processes have been performed to relax the original andimpure structures of the investigated bnnts. afterwards, the qcc parameters have been evaluated...
Theoretical study of the electronic structure, and nonlinear optical properties (NLO) analysis of 12-crown-4were done using Density Functional Theory (DFT) evaluations at the B3LYP/6-311G (d,p) level of theory. The optimized structure is nonlinear compound as indicated from the dihedral angles were presented. The calculated EHOMO and ELUMO energies of 12-Crown-4 (12CN4) ca...
Density Functional Theory (DFT) which is based on quantum mechanics theory has been broadly used to compute the energy and the structure of molecules and solids. However, the DFT method is limited when running calculations for a large system and only thousands of atoms can be solved. Alternatively, Molecular Dynamics (MD) simulation can be used to investigate the properties of the atomic system...
Theoretical study of the electronic structure, and nonlinear optical properties (NLO) analysis of 12-crown-4were done using Density Functional Theory (DFT) evaluations at the B3LYP/6-311G (d,p) level of theory. The optimized structure is nonlinear compound as indicated from the dihedral angles were presented. The calculated EHOMO and ELUMO energies of 12-Crown-4 (12CN4) ca...
In this study, quantum capacitance of graphene-based electrodes is evaluated using Density Functional Theory (DFT) calculations. The obtained results showed that quantum capacitance of graphene-based supercapacitors could be significantly improved by existence of structural defects on the graphene sheets at sufficiently high concentrations because of creating impure states resulted from carbon ...
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