نتایج جستجو برای: level hf 6 31g
تعداد نتایج: 1943981 فیلتر نتایج به سال:
A simple, efficient, and mild procedure for a solvent-free one-step synthesis of various 4,4'-diaminotriarylmethane derivatives in the presence of antimony trichloride as catalyst is described. Triarylmethane derivatives were prepared in good to excellent yields and characterized by elemental analysis, FTIR, (1)H and (13)C NMR spectroscopic techniques. The structural and vibrational analysis we...
By means of ab initio quantum chemical methods we have determined the energies and electronic structures of molecular wheels TiBn, TiBnN10 n, TiCnN10 n and TiCnB10 n (for n 1⁄4 0e10). The ground state energies and the corresponding spin states of each atom, cluster and molecular wheel were calculated first in the framework of Hartree-Fock self-consistent-field (HF-SCF) using minimal and more ac...
An electrostatically embedded generalized molecular fractionation with conjugate caps (EE-GMFCC) method is developed for efficient linear-scaling quantum mechanical (QM) calculation of protein energy. This approach is based on our previously proposed GMFCC/MM method (He; et al. J. Chem. Phys. 2006, 124, 184703), In this EE-GMFCC scheme, the total energy of protein is calculated by taking a line...
Geometric parameters and FT-IR spectrum of 6-bromo-8-thia-1,4epoxybicyclo[4.3.0]non-2-ene were computed by the HF, B3LYP, B3PW91 and mPW1PW91 methods in conjunction with the 6-31G(d,p) basis set. The calculated IR spectra are in a good agreement with the observed FT-IR spectrum. A general better performance of B3LYP, B3PW91 and mPW1PW91 versus HF was quantitatively characterized by using PAVF 1...
Glycine, Alanine and Valine are taken as amino acids with an equal polar head and with the difference in the length of hydrocarbon chains. The structural optimizations show the results of the isolated Glycine, Alanine and Valine in the gases phase, at the Hartree-Fock level by means of STO-3G,3-21G, 6-31G and 6-31+G basis sets. The calculations were performed for the ten (1-10) solvents using P...
In this study, paraphenylenediamine was first bonded to the fullerene and was optimized geometrically by Using the quantum chemistry methods. paraphenylenediamine was examined in the isolated state and in the fullerene-bonded state via carbon atoms. In the theoretical research, the simulation was done by the Gauss View software. Then, the bonding orbital calculation was done by using the NBO me...
polycyclic aromatic hydrocarbons (pahs) are a class of compounds consisting of more than twobenzene rings fused in a linear, angular, or clustered arrangement and do not contain hetero atomsor carry subsistent. pahs originate from various sources. they are primarily formed byincomplete combustion of carbon-containing fuels such as wood, coal, diesel, fat, or tobacco. thepresent study reports an...
Quaternisation of 3,5-diaryl-1,2,4-thiadiazoles with trimethylsilylmethyl triflate at 40 8C occurred at N-2. Separate desilylation of the salts resulted in a ring expansion to substituted 2H-1,3,5-thiadiazines 5. Heating of these with ethanolic sodium ethoxide caused sulfur extrusion and ring contraction to 2,4-disubstituted imidazoles 6. 3,4-Diaryl1,2,5-thiadiazoles were less reactive to alkyl...
The interaction of Fe2+ ion with Pyrazole was theoretically studied by Gussian 03, software at HF/(LanL2DZ+6-31G) and HF/ (LanL2DZ+6-31G (d)) levels in gas phase and solution. In this study acompartion between optimized structures of Pyrazole molecule in aspect of thermodynamicparameters such as enthalpy (H°), Gibbs free energy (G°) and entropy (S°) in presence of metallic ion(Fe2+), was perfor...
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