# Polarizable Potentials For Metals: The Density Readjusting Embedded Atom Method (DR-EAM)

## TL;DR

This paper introduces DR-EAM, an extension of the embedded atom method that models electronic polarization in metals by dynamically adjusting valence electron densities, enabling more accurate simulations of metallic interfaces and responses to external fields.

## Contribution

The paper presents DR-EAM, a novel modification of EAM that incorporates fluctuating valence densities to simulate electronic polarization effects in metals.

## Key findings

- Successfully models polarization and image charge effects.
- Predicts surface charging and shielding in electric fields.
- Shows charge transfer in alloys affecting unit cell geometries.

## Abstract

In simulations of metallic interfaces, a critical aspect of metallic behavior is missing from the some of the most widely used classical molecular dynamics force fields. We present a modification of the embedded atom method (EAM) which allows for electronic polarization of the metal by treating the valence density around each atom as a fluctuating dynamical quantity. The densities are represented by a set of additional fluctuating variables (and their conjugate momenta) which are propagated along with the nuclear coordinates. This ``density readjusting EAM'' (DR-EAM) preserves nearly all of the useful qualities of traditional EAM, including bulk elastic properties and surface energies. However, it also allows valence electron density to migrate through the metal in response to external perturbations. We show that DR-EAM can successfully model polarization in response to external charges, capturing the image charge effect in atomistic simulations. DR-EAM also captures some of the behavior of metals in the presence of uniform electric fields, predicting surface charging and shielding internal to the metal. We further show that it predicts charge transfer between the constituent atoms in alloys, leading to novel predictions about unit cell geometries in layered L$1_0$ structures.