A first principle study of electronic band structures and effective mass tensors of thermoelectric materials: PbTe, Mg2Si, FeGa3 and CoSb3

The state-of-the-art full-potential linearized augmented-plane wave methods have been employed to study the electronic structures of four thermoelectric materials PbTe, Mg2Si, FeGa3 and CoSb3 belonging to chalcogenide, silicide, correlated systems and skutterudite group, respectively. Here we used the PBEsol exchange correlation functional, which predicts lattice parameters very close to the experimental values. The calculated bulk moduli are also found to be in fairly good agreement with the experimental ones. In comparison to the experimental values this functional underestimates the band gap of Mg2Si and CoSb3; and overestimates the band gap of PbTe and FeGa3. The effect of spin–orbit coupling (SOC) on the electronic structures of these compounds is also studied in detail. There is a drastic decrement ( ∼ 90%) of band gap of PbTe in the presence of SOC whereas for rest of the compounds this decrement is within 17%. The effective mass tensors are calculated for those bands which are expected to influence the transport behaviour of the compounds.