Computing chemical potentials of solutions from structure factors

Abstract

The chemical potential of a component in a solution is defined as the free energy change as the amount of the component changes. Computing this fundamental thermodynamic property from atomistic simulations is notoriously difficult, because of the convergence issues in free energy methods and finite size effects. This paper presents the S0 method, which can be used to obtain chemical potentials from static structure factors computed from equilibrium molecular dynamics simulations under the isothermal-isobaric ensemble. The S0 method is demonstrated on the systems of binary Lennard-Jones particles, urea--water mixtures, a NaCl aqueous solution, and a high-pressure carbon-hydrogen mixture.