The influence of lattice dynamics on the electronic spectrum of CoSb3 skutterudite†
The behavior of electronic bands with temperature was studied in CoSb3 skutterudite by means of quantum molecular dynamics simulation. By averaging the electronic band structure along the molecular-dynamics trajectory it was found that thermal motion of ions leads to the decrease of the direct and indirect gaps with increasing temperature. This explains the observed effect of band convergence in CoSb3, and a good quantitative agreement with experimental results was obtained. The convergence effect was also found for the relative positions of the valence bands, emphasizing that the thermoelectric properties not only of the n-type material but also of the p-type material are affected. The results show that thermal vibrations of ions greatly affect the electronic spectrum of CoSb3.