Quantum Chemistry Calculated Intermolecular Interaction and Molecular Dynamics Simulation of Water and Methane
Date Issued
2011
Date
2011
Author(s)
Chen, Yu-De
Abstract
We have optimized the structures of methane monomer and water monomer at MP2/aug-cc-PVQZ, and also calculated the intermolecular interaction potentials of the methane-water dimer and water-water dimer using the Hartree-Fock self-consistent theory(HF)、correlation-corrected second-order Møller-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. The HF calculation yields repulsion, electrostatics and induction energies, and the MP2 calculation shows complete molecular interaction potentials. Then we have carried out the DFT calculations by eighty combinations of exchange-correlation functional and compare with the result of MP2. In addition, we have found that the basis set effect are significant, and calculated the complete basis limit.
After the calculation of potential energy surface is completed, we choose TIP4P modified model (TIP4P(M)) to fit the ab initio data. Then we construct the force field by the parameters we found, and perform the molecular dynamics simulation from its 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) and diffusion constant is acceptable. It shows that using the result of quantum chemistry computation to construct the force field can accurately reproduce the thermal properties.
Subjects
methane-water dimer
water-water dimer
Hartree-Fock (HF) Approximation
M?ller-Plesset (MP) perturbation theory
density functional theory (DFT)
coupled cluster(CC) method
Molecular Dynamics simulation
radial distribution function (RDF)
Velocity Autocorrelation Function (vaf)
Diffusion Constant
Type
thesis
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