نتایج جستجو برای: density functional theory dft

تعداد نتایج: 1668215  

 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...

حسینی , سیدمحمد, هاشمی , سیده هلن, کمپانی , احمد,

  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...

Amir Hossein Hakimyoun Hadi Bharifar Mohammad Ail Zarinfard Reza Ghiasi Simzar Hosseinzade

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...

2000
M. Ya. Amusia V. R. Shaginyan

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...

Journal: :iranian journal of catalysis 2014
mina ghiasi nahal majdoddin ebrahim esalati

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...

Journal: :journal of physical & theoretical chemistry 2011
a. nouni m. yousefi m. mirzaei

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...

2014
Weiyi Cao Alejandro H. Strachan Neil Armstrong

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...

تارقلی, احسان, صفی رحمانی‌فر, محمد, موسوی‌خوشدل, سید‌مرتضی,

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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