A new generalized Kohn-Sham method for fundamental band-gaps in solids

TL;DR

This paper introduces a generalized Kohn-Sham method combining LDA with a long-range exchange functional, accurately predicting solid-state band-gaps and properties with a novel range parameter formula.

Contribution

A new generalized Kohn-Sham approach that accurately predicts fundamental band-gaps using a range-dependent exchange functional with a specific formula for the range parameter.

Findings

Predicted band-gaps closely match experimental values for various solids.

Lattice constants and bulk moduli are similar to conventional LDA results.

The method effectively balances long-range exchange with local density approximation.

Abstract

We developed a method for calculating solid-state ground-state properties and fundamental band-gaps using a generalized Kohn-Sham approach combining a local density approximation (LDA) functional with a long-range explicit exchange orbital functional. We found that when the range parameter is selected according to the formula \gamma=A/(\eps_\inf - \eps_\tilde) where \eps_\inf is the optical dielectric constant of the solid and \eps_\tilde= 0.84 and A= 0.216a0^(-1), predictions of the fundamental band-gap close to the experimental values are obtained for a variety of solids of different types. For most solids the range parameter \gamma is small (i.e. explicit exchange is needed only at long distances) so the predicted values for lattice constants and bulk modulii are similar to those based on conventional LDA calculations.