# User-Defined Electrostatic Potentials in DFT Supercell Calculations: Implementation and Application to Electrified Interfaces

## TL;DR

This paper introduces a flexible method to apply custom electric fields in DFT calculations, enabling better study of electrified interfaces and electrochemical processes.

## Contribution

A new implementation for applying arbitrary electrostatic potentials in DFT supercell calculations using the VASP–Python interface.

## Key findings

- The implementation allows for energy and force corrections in electrified DFT simulations.
- The method was successfully applied to various systems like electrified surfaces and solid-water interfaces.
- The approach provides flexibility and control within standard VASP software.

## Abstract

Introducing electric fields into density functional theory
(DFT)
calculations is essential for understanding electrochemical processes,
interfacial phenomena, and the behavior of materials under applied
bias. However, applying user-defined electrostatic potentials in DFT
is nontrivial and often requires direct modification to the specific
DFT code. In this work, we present an implementation for supercell
DFT calculations under arbitrary electric fields and discuss the required
corrections to the energies and forces. The implementation is realized
through the recently released VASP–Python interface, enabling
the application of user-defined fields directly within the standard
VASP software and providing great flexibility and control. We demonstrate
the application of this approach with diverse case studies, including
molecular adsorption on electrified surfaces, field ion microscopy,
electrochemical solid–water interfaces, and implicit solvent
models.