For better understanding of conformational stability of the dipeptide model HCO—Gly—L—Leu—NH2,ab initio and DFT computations at HF/6-31G(4 6-311++G(d,p) and B3LYP/6-31G(d) levels oftheory were carried out. Geometry optimization of the dipeptide within the leucine (Leu) side chainangles (x2 ,x2) resulted in three stable conformations as followings: anti-anti, the most stable one,(Xi = 180°, x2 =...

Chromium and molybdenum are intermediate elements of a periodic table group, both of which are both low but essential in nutrition because they play a key role in the metabolism of the chemical activity of the body. Anion analysis of these compounds in order to compare the properties of the elements of the periodic table in one The group is from the periodic table. In this paper, the quantum ch...

We have performed first principles calculations to investigate the structure and electronic properties of several different Si–HfOx interfaces. The atomic structure has been obtained by growing HfOx layer by layer on top of the Si 100 surface and repeatedly annealing the structure using ab initio molecular dynamics. The interfaces are characterized via their geometric and electronic properties,...

We report the results of theoretical calculations on the optimized structures and relative energies between the D4d and D2 symmetry structures for double-decker type phthalocyanine compounds, Ti(Pc)2, Ti(Pc)2(+), Sn(Pc)2, Sn(Pc)2(+), Sc(Pc)2 and Sc(Pc)2(+), using eighteen types of functionals: B3LYP, B3PW91, B3P86, PBE1PBE, BHandHLYP, BPW91, BP86, M06, M06-2x, M06-HF, M06L, LC-BPW91, LC-ωPBE, C...

for better understanding of conformational stability of the dipeptide model hco—gly—l—leu—nh2,ab initio and dft computations at hf/6-31g(4 6-311++g(d,p) and b3lyp/6-31g(d) levels oftheory were carried out. geometry optimization of the dipeptide within the leucine (leu) side chainangles (x2 ,x2) resulted in three stable conformations as followings: anti-anti, the most stable one,(xi = 180°, x2 =...

the use of appropriate level of theories for studying weak interactions such as 8-8 stackinginteractions of aromatic molecules has been an important aspect, since the high level methods havelimitations for application to large molecules. the differences in the stacking energies of variousaromatic molecular structures are found significant. it is also very important for identifying the mostfavor...

Two-dimensi•,nal model calculations have been carried out of the distributions of the fluorinecontaining reservoir species HF, CF2 O, and CFC10. HF constitutes the largest fluorine reserr, fir in the stratosphere, but CF• O also makes an important contribution to the inorganic fluorine budget. CFC10 amounts are most irnportant in the tropical lower stratosphere. HF amounts increase with altitud...

Arguments showing that exchange-only optimized effective potential (xOEP) methods, with finite basis sets, cannot in general yield the Hartree-Fock (HF) ground state energy, but a higher one, are given. While the orbital products of a complete basis are linearly dependent, the HF ground state energy can only be obtained via a basis set xOEP scheme in the special case that all products of occupi...

The combination of Quantum Mechanics (QM) and Molecular Mechanics (MM) methods hasbecome alternative tool for many applications that pure QM and MM could not be suitable.The QM/MM method has been used for different type of problems, for example: structuralbiology, surface phenomena, and liquid phase. In this paper we have performed these methods forsome antibiotics and vitamins and then we comp...

Exciton effects on soliton and bipolaron lattice states are investigated using an electron-lattice Peierls model with long-range Coulomb interactions. The Hartree-Fock (HF) approximation and the single-excitation configurationinteraction (single-CI) method are used to obtain optical absorption spectra. We discuss the following properties: (1) The attraction between the excited electron and the ...