Electronic Structure of Calcium Hexaboride within the Weighted Density Approximation

TL;DR

This paper uses the weighted density approximation to accurately calculate the electronic structure of calcium hexaboride, revealing a semiconducting gap consistent with experiments, and discusses the improvements over local density approximation.

Contribution

The study demonstrates that WDA provides a more accurate description of CaB$_6$'s electronic structure than LDA, especially regarding the band gap.

Findings

WDA predicts a 0.8 eV band gap at the X point.

WDA results align with recent experimental data.

WDA reduces self-interaction errors compared to LDA.

Abstract

We report calculations of the electronic structure of CaB$_6$ using the weighted density approximation (WDA) to density functional theory. We find a semiconducting band structure with a sizable gap, in contrast to local density approximation (LDA) results, but in accord with recent experimental data. In particular, we find an $X$-point band gap of 0.8 eV. The WDA correction of the LDA error in describing the electronic structure of CaB$_6$ is discussed in terms of the orbital character of the bands and the better cancelation of self-interactions within the WDA.