화학공학소재연구정보센터
Journal of Chemical Physics, Vol.106, No.4, 1556-1568, 1997
An Effective Potential for Calculating Free-Energies .1. General Concepts and Approximations
We present a new analytical method to calculate free energies of molecules based on a high temperature expansion of an effective potential which is a function of the mean position and fluctuation of the coordinates of the molecule. We first introduce an effective potential V-eff((x) over bar,beta) which is a convex function of the mean position (x) over bar and whose sole minimum gives the free energy. Then, we define a convex effective potential V-eff((x) over bar,Delta,beta) which after variation over the mean fluctuation Delta yields V-eff((x) over bar,beta). We expand V-eff((x) over bar,Delta,beta) in a high temperature series, The first two terms of the series yield an effective diffused potential method to calculate free energies. The diffusion times are calculated via a variational principle. Besides free energies, the method yields an analytical annealing method for energy minimization.