THE CHEMICAL POTENTIAL IN ATOMICALLY INHOMOGENEOUS FLUIDS IN EXTERNAL FORCE FIELDS BY COMPUTER SIMULATION

The accuracy and practicality of the Widom fictitious‐particle insertion method for determining the chemical potential is tested for very inhomogeneous fluids in strong external potentials by a series of molecular dynamics computer simulations. The chemical potential determined in this way is found, as predicted, on an atomic scale to be independent of position in the fluid to a few percent even when the density varies by up to a factor 80. This severe test means that this method of determining chemical potential is established as reliable and accurate in any well‐found computer simulation even when the system is very inhomogeneous.