Categorization of surface polarity from a crystallographic approach

TL;DR

This paper introduces an efficient algorithm to classify surface polarity in crystallography, aiding the preparation of nonpolar slabs for ab initio calculations by analyzing surface orientations and potential reconstructions.

Contribution

The paper presents a novel algorithm based on isometries to determine surface polarity and guide the creation of nonpolar, stoichiometric slabs from bulk crystals.

Findings

Algorithm accurately classifies surface polarity.

Provides guidance for slab cleaving and reconstruction.

Facilitates improved ab initio surface modeling.

Abstract

With ab initio codes that employ three-dimensional periodic boundary conditions, the slab-and-vacuum model has proven invaluable for the derivation of energetic, atomistic, and electronic properties of materials. Within this approach, polar and nonpolar slabs require different levels of treatment, as any polar instability must be compensated on a case-by-case basis in the former. This article proposes an efficient algorithm based on isometries to identify whether a slab with the given surface orientation would be intrinsically polar, and if not, to obtain information on where to cleave the bulk crystal to obtain a stoichiometric nonpolar slab and whether reconstruction is necessary to generate a stoichiometric slab that is not polar.