A generalized approach for rapid entropy calculation of liquids and solids

TL;DR

This paper introduces a unified, rapid method for calculating the total entropy of liquids and solids using a single molecular dynamics trajectory, combining electronic, vibrational, and configurational entropy components.

Contribution

It presents a novel comprehensive approach that efficiently computes all entropy components from a single MD simulation, applicable to both solids and liquids.

Findings

Method accurately characterizes thermodynamic states.

Efficiently computes melting temperatures.

Versatile across different phases.

Abstract

We build a comprehensive methodology for the fast computation of entropy across both solid and liquid phases. The proposed method utilizes a single trajectory of molecular dynamics (MD) to facilitate the calculation of entropy, which is composed of three components. The electronic entropy is determined through the temporal average acquired from density functional theory (DFT) MD simulations. The vibrational entropy, typically the predominant contributor to the total entropy, even within the liquid state, is evaluated by computing the phonon density of states via the velocity auto-correlation function. The most arduous component to quantify, the configurational entropy, is assessed by probability analysis of the local structural arrangement and atomic distribution. We illustrate, through a variety of examples, that this method is both a versatile and valid technique for characterizing the thermodynamic states of both solids and liquids. Furthermore, this method is employed to expedite the calculation of melting temperatures, demonstrating its practical utility in computational thermodynamics.