Efficient periodic density functional theory calculations of charged molecules and surfaces using Coulomb kernel truncation

TL;DR

This paper introduces a method to perform efficient DFT calculations of charged molecules and surfaces under 0D and 2D periodic boundary conditions by using Coulomb kernel truncation, enabling accurate electrostatic potential computations without nonphysical artifacts.

Contribution

The authors develop a Coulomb kernel truncation approach combined with padding to accurately compute electrostatic potentials for charged systems under 0D and 2D boundary conditions in DFT calculations.

Findings

Efficient large supercell calculations of charged defect formation energies.

Long time-scale molecular dynamics simulations of electrode-electrolyte interfaces.

Removal of nonphysical potentials in vacuum regions for 0D and 2D systems.

Abstract

Density functional theory (DFT) calculations of charged molecules and surfaces are critical to applications in electro-catalysis, energy materials and related fields of materials science. DFT implementations such as the Vienna ab-initio Simulation Package (VASP) compute the electrostatic potential under 3D periodic boundary conditions, necessitating charge neutrality. In this work, we implement 0D and 2D periodic boundary conditions to facilitate DFT calculations of charged molecules and surfaces respectively. We implement these boundary conditions using the Coulomb kernel truncation method. Our implementation computes the potential under 0D and 2D boundary conditions by selectively subtracting unwanted long-range interactions in the potential computed under 3D boundary conditions. By combining the Coulomb kernel truncation method with a computationally efficient padding approach, we remove nonphysical potentials from vacuum in 0D and 2D systems. To illustrate the computational efficiency of our method, we perform large supercell calculations of the formation energy of a charged chlorine defect on a sodium chloride (001) surface and perform long time-scale molecular dynamics simulations on a stepped gold (211) | water electrode-electrolyte interface.