The chemical potential of water: molecular dynamics computer simulation of the CF and SPC models

Abstract

The excess Helmholtz free energy Δ A of two models of water, the revised central force model and the simple point charge model, has been calculated by molecular dynamics computer simulation. The method of “thermodynamic integration” has been used to calculate the free energy difference between the (model) water and an ideal gas of molecules at the same temperature and volume. For this particular thermodynamic property, Ewald sums and truncated potentials yield the same results.