Electronic Excitations from a Perturbative LDA+GdW Approach

TL;DR

This paper presents a fast, perturbative LDA+GdW method for calculating electronic excitations in various systems, offering a good balance between accuracy and computational efficiency.

Contribution

It introduces a perturbative approach to MBPT that simplifies dielectric screening calculations, applicable to bulk and reduced-dimensional systems, improving speed while maintaining reasonable accuracy.

Findings

Efficient approximation for quasiparticle corrections in DFT-LDA.

Applicable to diverse systems including bulk, molecules, and interfaces.

Results show slightly less accuracy but significantly faster calculations.

Abstract

We discuss an efficient approach to excited electronic states within ab-initio many-body perturbation theory (MBPT). Quasiparticle corrections to density-functional theory result from the difference between metallic and non-metallic dielectric screening. They are evaluated as a small perturbation to the DFT-LDA band structure, rather than fully calculating the self energy and evaluating its difference from the exchange-correlation potential. The dielectric screening is desribed by a model, which applies to bulk crystals, as well as, to systems of reduced dimension, like molecules, surfaces, interfaces, and more. The approach also describes electron-hole interaction. The resulting electronic and optical spectra are slightly less accurate but much faster to calculate than a full MBPT calculation. We discuss results for bulk silicon and argon, for the Si(111)-(2x1) surface, the SiH4 molecule, an argon-aluminum interface, and liquid argon.