"Configurational Free energy" : Direct free energy calculations in molecular systems

TL;DR

This paper introduces a novel statistical mechanical framework for directly calculating the free energy of molecular systems by sequentially removing molecules, enabling free energy evaluation across different densities.

Contribution

It presents a new method for direct free energy calculation in molecular systems using a single-step molecular deletion approach, linking configurational microstates to free energy.

Findings

Allows free energy evaluation as a function of density.

Provides a configurational free energy expression based on microstates.

Capable of computing free energy from simulated density to zero.

Abstract

In this work, I propose a statistical mechanical framework, for the evaluation of the free energy in molecular systems, by "deleting" all the molecules in a "single" step. The approach can be considered as the statistical mechanics equivalent of the evaluation of the potential energy in classical mechanics by accounting for the necessary work to transfer all molecules one by one to infinite distance. As a result, the free energy of an atomistic system, can now be expressed, as an ensample average over a configurational function that we shall call "configuretional free energy" and correspondent to the contribution of each configurational microstate, to the free energy of the system, provided that the microstates are sampled according to the equilibrium statistics. Moreover, the proposed method is capable of evaluating, the free energy as a function of the density, from the simulated density down to zero.