Electronic structure and thermoelectric properties of CoAsSb with post-DFT approaches

TL;DR

This study assesses various post-DFT computational methods to accurately predict the electronic structure and thermoelectric properties of CoAsSb, highlighting the effectiveness and limitations of bandgap corrections across methods.

Contribution

It evaluates the impact of different advanced electronic structure methods on thermoelectric predictions and tests the common practice of rigid band shifts for accuracy enhancement.

Findings

Rigid shifts improve Seebeck coefficient agreement across methods.

Differences in thermoelectric bandgap persist despite shifts.

Temperature dependence varies between computational approaches.

Abstract

We study the electronic structure and thermoelectric properties of recently synthesized CoAsSb. The calculated bandgap becomes more accurate for increasingly-complex electronic structure methods: generalized gradient approximation, hybrid functionals, self-consistent linearized quasiparticle GW method (LQSGW), and LQSGW with simplified vertex corrections. By equating the bandgaps of each method from a rigid shift of the bands, we evaluate the contributions made to thermoelectric properties beyond the bandgap. In doing so, we evaluate the efficacy of a common-practice: a rigid shift applied to less-costly electronic structure methods in order to gain some accuracy of the more-costly methods. We find that while the shift made the Seebeck coefficients much closer to one another than from the original electronic structures, there remain differences in the Goldsmid-Sharp (thermoelectric) bandgap between the methods and from the intended electronic bandgap. Additionally, some lasting differences in temperature dependence remain between the methods.