فهرست مقالات Basis sets

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  1 - Investigation of solvent effect on the active site energy of Carbonic Anhydrase and Ribonucleotide Reductase
  M. Heshmat S. Saki M. Khaleghian S. Irani M. Monajjemi
  Enzymes catalyze many biological reactions. The rates of chemical reaction in the presence ofenzymes are, in some cases, accelerated more than 10 orders of magnitude relative to thecorresponding rates in solution.In this paper a comparison between optimized structures o چکیده کامل

  Enzymes catalyze many biological reactions. The rates of chemical reaction in the presence ofenzymes are, in some cases, accelerated more than 10 orders of magnitude relative to thecorresponding rates in solution.In this paper a comparison between optimized structures of two enzyme molecules in aspect ofenergy and dipole moment in different conditions including presence of metallic ion, withoutmetallic ion and in the presence of substrate molecule was performed. The stabilizing effect ofmetallic ion is clearly seen. The calculations were performed with three basis sets: 6-31G, 6-31G*and 6-31G** and 6 different solvents and in vacuum. We conclude that the addition of polarizedfunctions to basis sets cause to create higher energy level of system. پرونده مقاله
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  2 - Rationalizing the Strength of Hydrogen-Bonded of Molybdate-Phosphonic acid Complex (1:2): Density Functional Theory Studies
  Mohammad Hossein Ghorbani Hossein Aghaei
  The relative stability of hydrogen-bonded of Molybdate-Phosphonic Acid (MPA) complex (1:2) ingas phase has been carried out using Density Functional Theory (DFT) methods. The methods are usedfor calculations are B3LYP, BP86 and B3PW91 that have been studied in two serie چکیده کامل

  The relative stability of hydrogen-bonded of Molybdate-Phosphonic Acid (MPA) complex (1:2) ingas phase has been carried out using Density Functional Theory (DFT) methods. The methods are usedfor calculations are B3LYP, BP86 and B3PW91 that have been studied in two series of basis sets: D95**and 6-31+G(d,p) for hydrogen and oxygen atoms; LANL2DZ for Mo and Phosphorus. Predictedhydrogen-bond geometry and relative stability are discussed. Equilibrium geometry in the groundelectronic state energy has been calculated for 1:2 complex. The best results for energetics and geometryof the ground state was obtained with BP86 calculations. پرونده مقاله
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  3 - Quantum Chemistry Study & Evaluation of Basis Set Effects on Prediction of Amino Acids Properties:
  M. Monajjemi M. Karimkhan M. R. Gholami A. Ziglari K. Zare S. Afsharnezhad
  The potential energy surface of gaseous glycine determined years ago in the ab initio B3LYP/6-311++G** calculations is composed of thirteen stable conformers. We performed the ab initiomolecular orbital calculations as the starting point to carry out a force field and n چکیده کامل

  The potential energy surface of gaseous glycine determined years ago in the ab initio B3LYP/6-311++G** calculations is composed of thirteen stable conformers. We performed the ab initiomolecular orbital calculations as the starting point to carry out a force field and normal coordinatecalculation on the most stable conformer of non-zwitterionic glycine [conformer (I)]. Thecalculations were carried out at different levels of theory using two methods, namely, the Hartree-Fock (HF) and the Möller-Plesset second order perturbation (MP2) method (including electroncorrelation), and using the Pople’s basis sets, namely, STO-nG (n=2, 3 and 6), 3-21G, 6-21G, 6-31G, 6-311G and also cc-pVnZ to obtain HF limit. This different basis sets accompanied with thedifferent combinations of diffuse and polarization functions were used. Each level of theory, withno symmetry restrictions, did fully optimization of neutral glycine. The atomic chargedistributions were obtained using the Mulliken population analysis. The structural characteristicssuch as the total energies, the complete optimized geometrical parameters including bond lengths,normal and torsion angles, as well as dipole moments, rotational constants, atomic chargedistributions, vibrational frequencies and IR intensities of the equilibrium conformation of glycinein gas phase were calculated at a wide range of the levels of theory -as mentioned above- and theresults were compared together and with HF limit and the experimental data to examine thereliability of the applied basis sets and to introduce the most efficient ones. We also assayed howthe strength of internal H-bonds depended on the variant parameters of basis set via the calculatedatomic charges. پرونده مقاله