Charged surfaces and slabs in periodic boundary conditions

TL;DR

This paper introduces a self-consistent method to improve the convergence of energies and charge distributions in 2D periodic charged systems within plane wave DFT calculations, addressing slow convergence caused by spurious electric fields.

Contribution

A novel self-consistent technique that accelerates convergence of energies and charge densities for charged surfaces in 2D periodic boundary conditions.

Findings

Significantly faster convergence of energies with cell size.

Reduced impact of spurious electric fields on calculations.

Enhanced accuracy in modeling charged surfaces.

Abstract

Plane wave density functional theory codes generally assume periodicity in all three dimensions. This causes difficulties when studying charged systems, for instance energies per unit cell become infinite, and, even after being renormalised by the introduction of a uniform neutralising background, are very slow to converge with cell size. The periodicity introduces spurious electric fields which decay slowly with cell size and which also slow the convergence of other properties relating to the ground state charge density. This paper presents a simple self-consistent technique for producing rapid convergence of both energies and charge distribution in the particular geometry of 2D periodicity, as used for studying surfaces.