Crystal-liquid interfacial free energy via thermodynamic integration

TL;DR

This paper introduces a new thermodynamic integration method using Gaussian walls to accurately compute crystal-liquid interfacial free energy in molecular dynamics, overcoming previous hysteresis issues.

Contribution

A novel TI scheme with Gaussian walls is developed to measure interfacial free energy, addressing hysteresis and finite-size effects in molecular simulations.

Findings

Successfully applied to Lennard-Jones system for multiple crystal orientations.

Demonstrated finite-size scaling to estimate thermodynamic limit.

Showed TI scheme does not suppress capillary wave fluctuations.

Abstract

A novel thermodynamic integration (TI) scheme is presented to compute the crystal-liquid interfacial free energy ($\gamma_{\rm cl}$) from molecular dynamics simulation. The scheme is applied to a Lennard-Jones system. By using extremely short-ranged and impenetrable Gaussian flat walls to confine the liquid and crystal phases, we overcome hysteresis problems of previous TI schemes that stem from the translational movement of the crystal-liquid interface. Our technique is applied to compute $\gamma_{\rm cl}$ for the (100), (110) and (111) orientation of the crystalline phase at three temperatures under coexistence conditions. For one case, namely the (100) interface at the temperature $T=1.0$ (in reduced units), we demonstrate that finite-size scaling in the framework of capillary wave theory can be used to estimate $\gamma_{\rm cl}$ in the thermodynamic limit. Thereby, we show that our TI scheme is not associated with the suppression of capillary wave fluctuations.