Based on Quantum Chemistry Method to Calculate Intermolecular Interactions and Molecular Dynamics Simulations of Methane Fluids
Date Issued
2010
Date
2010
Author(s)
Tu, Kuang-Wei
Abstract
We have calculated the interaction potentials of the “ Inert gas-Inert gas ” and 3 “ Inert gas-Methane ” using the Hartree-Fock (HF) self-consistent theory, the correlation-corrected second-order Møller-Plesset (MP2) perturbation theory, and the density functional theory (DFT). The HF calculations yield repulsive potentials, and the DFT calculations can compare with the accurate MP2 results to find out the suitable functions for “ Inert gas-Methane ”.Then we use Mixing rule to calculation the “Inert gas-Methane” interaction from the “Methane-Methane”and “Inert gas-Inert gas” ab initio data, and found that the result have good agreement with the “Inert gas-Methane” ab initio data ,if we regard methane molecular as a large inert gas atom.
We use four kinds of site-site-fitting models to fit the results of quantum chemistry calculation.We can get the parameters for Lennard-Jones potentials of bond lengths and binding energies and then input them to build force fields. To simulate the equilibrium properties at T=92K, P=5MPa, T=150K, P=100MPa, T=370K, P=51MPa, P=61MPa, P=77MPa and dynamics properties of methane liquid along the vapor-liquid curve. 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.
Subjects
Hretree-Fock approximation
M?ller-Plesset perturbation theory
Density functional theory
Mixing rule
Radial distribution function
autocorrelation function
Diffusion coefficient
Shear viscosity
Thermal conductivity
Gaussian 03 package
Type
thesis
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