Calculation of Free Energy from the Internal-Energy Distribution Function

ABSTRACTWe outline a new method for the calculation of free energies from a cumulant analysis of the internal-energy distribution function obtained from a Monte-Carlo simulation. The new methodology is validated by comparing the free energy calculated for a perfect crystal from this approach with the free energy calculated by a temperature integration scheme. By comparing the two methods for an inhomogeneous system containing grain boundaries, we investigate the effects of the local-strain distribution on the free energy; for the superlattice of twist grain boundaries studied here, the effects are found to be small.