Direct calculation of the ionic mobility in superionic conductors

TL;DR

This paper introduces a first-principles non-equilibrium molecular dynamics method to accurately calculate ionic mobility in superionic conductors, effectively capturing ion-ion correlations with lower computational effort.

Contribution

The paper presents a novel NEMD-based approach for calculating ionic mobility that accounts for ion-ion interactions more efficiently than existing methods.

Findings

Accurately estimates ionic mobilities of $ ext{α}$-AgI and $ ext{α}$-RbAg$_4$I$_5$

Provides good agreement with experimental data

Offers a computationally efficient alternative to traditional methods

Abstract

We describe an approach based on non-equilibrium molecular dynamics (NEMD) simulations to calculate the ionic mobility of solid ion conductors such as solid electrolytes from first-principles. The calculations are carried out in finite slabs of the material, where an electric field is applied and the dynamic response of the mobile ions is measured. We compare our results with those obtained from diffusion calculations, under the non-interacting ion approximation, and with experiment. This method is shown to provide good quantitative estimates for the ionic mobilities of two silver conductors, $\alpha$-AgI and $\alpha$-RbAg$_4$I$_5$. In addition to being convenient and numerically robust, this method accounts for ion-ion correlations at a much lower computational cost than exact approaches.