An Enhanced Sampling Approach for Computing the Free Energy of Solid Surface and Solid-Liquid Interface

Abstract

Free energies of a solid surface and a solid-liquid interface play significant roles in thermodynamics. Due to the limited availability of experimental data, computational methods offer effective alternatives for calculating these properties. This study adopts advanced frameworks of the logarithmic mean force dynamics method to present an enhanced sampling approach for the calculation of the free energy at different temperatures. To achieve this, the free energy profile is constructed along with a pre-established collective variable within the melting transition and cleavage processes. The values of the solid surface and solid-liquid interface free energies are then extrapolated from the excess free energy related to the formation and persistence of the solid surface or the solid-liquid interface. Furthermore, this methodology is employed to calculate the temperature dependence of the free energy measurements for the (100) and (110) surfaces and interfaces of Cu. It is shown that this methodology is robust and readily applicable in contemporary models of atomic interactions and various systems. A generalized but as simple as possible approach that can be applied to compute both the free energy of the solid-liquid interface and the solid surface is presented. The approach is based on enhanced sampling methods that can compute the interfacial free energy at various temperatures, orientations, and across a wide range of systems.image