Quantum Chemistry Calculated Intermolecular Interaction and Molecular Dynamics Simulation of Cyclopropane

• Main Authors: Yen-Ching Ho, 何彥慶
• Other Authors: 趙聖德
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/30300280241269511032

碩士 === 國立臺灣大學 === 應用力學研究所 === 105 === The first topic of this research is quantum chemistry calculation to cyclopropane. We have calculated the intermolecular interaction energy of the cyclopropane dimer with Hatree-Fock self-consistent theory(HF), second-order M?ller-Plesset perturbation theory(MP2), density functional theory(DFT) and coupled cluster(CC) method, and the correction of the basis-set superposition error(BSSE) has been included. In the structure optimization and binding energy calculations of cyclopropane, we employed MP2 method with Pople’s series basis sets (6-31(G) up to 6-311++G(3df,3pd)) and Dunning’s correlation consistent basis sets(cc-pVXZ (X=D、T)and aug-cc-pVXZ, (X=D、T、Q). In addition, single-point coupled cluster with single and double and perturbative triple excitation (CCSD(T)) calculations were carried out to calibrate the MP2’s binding energy. For 15 cyclopropane conformers, the HF calculation yields repulsion, electrostatics and induction energies, and the MP2 calculation shows full potential curves. In the other hand, PSI4 software was utilized through SAPT method to decompose the intermolecular interaction into four parts, as electrostatic energy、 induction energy、 dispersion energy、 exchange energy, to analyze the repulsion and attraction effect on stability of cyclopropane dimer. After the quantum chemistry calculation is completed, we choose 9site model with Lennard-Jones potential to fit the ab initio data, and construct the force field by the parameters we found. Then perform the molecular dynamics simulation from cyclopropane’s triple point to the critical point along the gasification curve with different temperatures and corresponding densities. In addition, we compare the equilibrium and dynamic properties with the experiment data and previous investigations. The comparison of the radial distribution function (RDF), velocity autocorrelation function (VAF), diffusion constant and shear viscosity is acceptable. It shows that using the result of quantum chemistry computation to construct the force field can accurately reproduce the thermal properties.