Van der Waals parameters of inert, polar and non-polar gas molecules obtained from atomistic molecular dynamics simulations

Abstract

A series of atomistic molecular dynamics simulations were performed on the systems of gas molecules within an NVT ensemble, where the number of molecules, the volume and the temperature were controlled. For each simulation, simulated annealing technique was used to gradually vary the temperature and the change in gas pressure was measured within the simulation box at constant volume. Simulation results and regression analysis on the relationships between pressure and temperatures showed that two van der Waals parameters, representing interaction strength and effective size of the gas molecules, depended on shape, size and polarity of the molecules. This study provided an alternative way of demonstrating the basic thermodynamics of gas, and bridging the gap between information from microscopic and macroscopic scales.