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

TL;DR

This paper presents a flexible implementation for applying user-defined electric fields in supercell DFT calculations using VASP, enabling advanced studies of electrochemical and interfacial phenomena.

Contribution

The authors developed a VASP-Python interface-based method for arbitrary electric field application in DFT, with corrections for energies and forces, demonstrated through diverse case studies.

Findings

Enabled DFT calculations with user-defined electric fields in VASP.

Applied the method to molecular adsorption, microscopy, and electrochemical interfaces.

Provided corrections for energies and forces under applied fields.

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.