Ab initio electronic structure of quasi two-dimensional materials: a "native" gaussian--plane wave approach

TL;DR

This paper introduces a new ab initio computational approach tailored for quasi-2D materials, using basis functions that are periodic in-plane and atomic-like out-of-plane, improving accuracy for layered structures.

Contribution

The authors develop a native quasi-2D basis for electronic structure calculations, integrating DFT, GW, and Bethe-Salpeter methods, addressing limitations of 3D periodic codes.

Findings

New basis improves treatment of long-range Coulomb interactions.

Enhanced accuracy in modeling external fields and structural deformations.

Applicable to various layered materials with complex electronic properties.

Abstract

Ab initio electronic structure calculations of two-dimensional layered structures are typically performed using codes that were developed for three-dimensional structures, which are periodic in all three directions. The introduction of a periodicity in the third direction (perpendicular to the layer) is completely artificial and may lead in some cases to spurious results and to difficulties in treating the action of external fields. In this paper we develop a new approach, which is "native" to quasi-2D materials, making use of basis function that are periodic in the plane, but atomic-like in the perpendicular direction. We show how some of the basic tools of ab initio electronic structure theory -- density functional theory, GW approximation and Bethe-Salpeter equation -- are implemented in the new basis. We argue that the new approach will be preferable to the conventional one in treating the peculiarities of layered materials, including the long range of the unscreened Coulomb interaction in insulators, and the effects of strain, corrugations, and external fields.