DETAILED BALANCE METHOD FOR CHEMICAL-POTENTIAL DETERMINATION IN MONTE-CARLO AND MOLECULAR-DYNAMICS SIMULATIONS

We present a new, nondestructive, method for determining chemical pote ntials in Monte Carlo and molecular dynamics simulations. The method e stimates a value for the chemical potential such that one has a balanc e between fictitious successful creation and destruction trials in whi ch the Monte Carlo method is used to determine success or failure of t he creation/destruction attempts; we thus call the method a detailed b alance method. The method allows one to obtain estimates of the chemic al potential for a given species in any closed ensemble simulation; th e closed ensemble is paired with a ''natural'' open ensemble for the p urpose of obtaining creation and destruction probabilities. We present results for the Lennard-Jones system and also for an embedded atom mo del of liquid palladium, and compare to previous results in the litera ture for these two systems. We are able to obtain an accurate estimate of the chemical potential for the Lennard-Jones system at higher dens ities than reported in the literature.