Application Of Computational Chemical In Methane Hydrate, Ph₃PCl₂ And Protein Strutural Prediction

Modern quantum chemical density functional theory and ab initio have been an important method to study the chemical question, to be used to calculate and predict the approach of chemical reaction, mechanism and transition etc. Just like experimental science . theoral computer chemistry has been the part of the chemist everyday work. In the past three years. I have studied the basic theory and knowledge of quantum chemistry from my tutor, and have made use of quantum chemistry computer software to calculate serval molecular system, obtained a large number of practical experience.This paper include two parts briefly, from one to four chapter is the first part, the two chapters introduced the knowledge of quantum chemistry and the current used computer method, the intermolecular interaction and gas hydrate. we process the calculation of Molecular Potential Energies in Methane Hydrate Structure-I Unit C(?)ll in the third chapter. We used the Fortran 90 program to write the coordinate procedure of the all atoms of Methane Hydrate Structure-I Unit Cell, the atom space coordinate is the function of the side l. On the personal computer, use the Gaussian program, Hartree-Fock, DFT (PLYP, B3LYP. MPW1PW91, and SVWN) and MP2 methods to study the intermolecular potential functions for the unit cell of methane hydrate structure-I. The unit cell is treated as a regular dodecahedron including 20 water molecules and a methane molecule in the center. The geometry of methane is optimized by ab initio HF/6-31G(d, p) and the water molecules take the geomet(?)y of an ST2 model. The wate(?)-water hydrogen bond potential E_hb(l) and water-methane van der Waals potential E_vdw(l) as functions of the side length l are calculated, keeping the molecular geometries of water and methane fixed. Then MP2 calculations arc performed at several key points. In all calculations we use the 6 31G(d,p) basis set. Basis set superposition error (BSSE) is corrected and the upper and lower limits of BSSE are determined for the water-water hydrogen bond energy. In the forth chapter, we choose the four distinct stationary points on the Ph₃PCl₂ molecular energy surface, use the density functional theory(DFT), B3LYP/6-31G(d,p), calculate the energy, charge, bond length, bond angle, chemical shift and coupled canstants of the four structure, get the useful parameters.The second part includes 5 and 6 two chapters. The contents is Amino Acid Principal Component Analysis (PCA) for Protein Structural Study and Its Application in Structure Prediction on the basis of bioinformatics. At first we introduced the concept of bioinformatics, the research contents, the characteristic and the prospect. In the sixth chapter...