Voltage equilibration for reactive atomistic simulations of electrochemical processes

TL;DR

EChemDID is a novel simulation method that models voltage equilibration in reactive molecular dynamics, enabling accurate study of electrochemical processes and device behaviors at the atomic level.

Contribution

The paper introduces EChemDID, a new approach to simulate electrochemical voltage effects within reactive molecular dynamics, including dynamic potential equilibration in metallic structures.

Findings

Accurately describes electric fields generated by applied voltage.

Predicts switching behavior in electrochemical metallization cells.

Demonstrates potential for modeling energy conversion devices.

Abstract

We introduce EChemDID, a model to describe electrochemical driving force in reactive molecular dynamics simulations. The method describes the equilibration of external electrochemical potentials (voltage) within metallic structures and their effect on the self consistent partial atomic charges used in reactive molecular dynamics. An additional variable assigned to each atom denotes the local potential in its vicinity and we use fictitious, but computationally convenient, dynamics to describe its equilibration within not-simply connected metallic structures on-the-fly during the molecular dynamics simulation. This local electrostatic potential is used to dynamically modify the atomic electronegativities used to compute partial atomic changes via charge equilibration. Validation tests show that the method provides an accurate description of the electric fields generated by the applied voltage and the driving force for electrochemical reactions. We demonstrate EChemDID via simulations of the operation of electrochemical metallization cells. The simulations predict the switching of the device between a high-resistance to a low-resistance state as a conductive metallic bridge is formed and resistive currents that can be compared with experimental measurements. In addition to applications in nanoelectronics, EChemDID could be useful to model electrochemical energy conversion devices.