Topological analysis of electron density in half-Heusler ZrXBi (X = Co, Rh) compounds: A density functional theory study accompanied by Bader's quantum theory of atoms in molecules

Abstract

Here, we study the electron charge densities (ECDs) of two half-Heusler compounds, i.e. ZrCoBi and ZrRhBi, from topological point of view using the combination of DFT and quantum theory of atoms in molecules (DFT + QTAIM). We also investigate the structural properties and electronic structures of these compounds including DOSs, band structures and electron charge densities (ECDs) as well as the thermoelectric parameters including Seebeck coefficient and electrical conductivity. Furthermore, the effects of pressure on the properties of these compounds are investigated. The DFT + QTAIM calculations show that the compounds under study have similar numbers and types of critical points, but different bonds properties. The bonds of the Rh-case are more stable than those of the Co-case. Moreover, the ECD values at bonds of Rh-case are more than the Co-case. Imposing pressure affects some properties of the bonds in both cases, but does not change the numbers and types of their critical points. Based on our electronic structure calculations, Co-case has sharper valence DOSs near the Fermi level and larger band gap compared to the Rh-case. We have also observed flatter bands in the Co-case near the Fermi level compared to the Rh-case. In the anticipation of further study, the presented results may provide fundamental information which can pave the way for the study on the thermoelectric efficiencies of these interesting thermoelectric materials. In agreement with the electronic structure, our thermoelectric calculations show higher Seebeck coefficient and lower electrical conductivity for ZrCoBi than ZrRhBi. © 2020 Elsevier B.V.