Exact-exchange density-functional calculations for noble-gas solids

TL;DR

This paper evaluates the performance of the exact-exchange density functional method for noble-gas solids, finding it reproduces optical gaps well but fails to accurately predict energy gaps and structural properties due to missing Van der Waals interactions.

Contribution

It provides a comparative analysis of EXX and LDA methods for noble-gas solids, highlighting limitations in gap prediction and structural accuracy.

Findings

EXX reproduces about 80% of experimental optical gaps

EXX does not accurately reproduce fundamental energy gaps

Both EXX and LDA poorly predict structural properties due to missing Van der Waals interactions

Abstract

The electronic structure of noble-gas solids is calculated within density functional theory's exact-exchange method (EXX) and compared with the results from the local-density approximation (LDA). It is shown that the EXX method does not reproduce the fundamental energy gaps as well as has been reported for semiconductors. However, the EXX-Kohn-Sham energy gaps for these materials reproduce about 80 % of the experimental optical gaps. The structural properties of noble-gas solids are described by the EXX method as poorly as by the LDA one. This is due to missing Van der Waals interactions in both, LDA and EXX functionals.