Quantum Chemistry Calculated Intermolecular Interactions with Methane-Silane dimers andMolecular Dynamics simulations of Methane Fluids
| Autor: | Shih-Wei Chao, 趙士緯 |
|---|---|
| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 We have calculated the interaction potentials of the 12 methane-silane conformations using the Hartree-Fock (HF)self-consistent theory, the correlation-corrected second-order Møller-Plesset (MP2) perturbation theory, and the density functional theory (DFT) with the basis set superposition error (BSSE) corrected. The HF calculation yield repulsive potentials and converged at the cc-pVQZ basis set after quantitatively calculation. The MP2 calculation yield whole van der waals potential curves. The basis set effect are observable, and the calculation converged in 0.05kca/mol. Moreover, change the C-Si position of the six non-symmetric conformers will yield different HF and MP2 calculations. The DFT calculations generate a wide range of interaction patterns, and compare with MP2 results. We use Mixing rule to calculation the methane-silane interaction from the methane-methane and silane-silane ab initio data, and found that the result have good agreement with the methane-silane ab initio data in E、F、I、J conformers. Others are corrigible with the electrostatic. Next, we use 4 sites-fitting method to fit the results of quantum chemistry calculation. We can get the force parameters of bond lengths and binding energies and then input them to solve Newton''s equations. To simulate the equilibrium properties and dynamics properties of methane liquid, we perform NVT ensemble molecular dynamics simulations. We compare the results with experiments from different research groups, and found that our PES is capable of reproducing the experimental data within the error bars. It demonstrates that quantum chemistry calculated intermolecular interaction is very good which can accurately yield the molecular dynamic simulation results. Beside we simulate the equilibrium properties and dynamic properties along the vapor-liquid curve and solid-liquid curve in the phase diagram using three potential models which can help us to realize the feature of different phase. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|