Minimization of the free energy under a given pressure by natural iteration method

Natural iteration method within the Cluster Variation Method is coupled with zero potential to minimize the free energy under the constraint of a constant pressure. The calculated results reproduce the ones obtained by the conventional method in which a gradient of the free energy curve is estimated at each atomic distance. It is noted that the computation time is much reduced in the present scheme and, therefore, it has a potential applicability in the future calculations with a free energy containing a larger number of variables.