The role of electronic and crystal structure in the effect of volumetric band convergence

The effect of rearrangement of the electronic band structure by changing the volume of a crystalline cell was investigated by means of first-principles calculation. The corresponding effect on the thermoelectric power factor was studied in Boltzmann approximation. The separate role of electronic structure of constituent elements and crystal structure was investigated. As the example, cubic Mg2Si and orthorhombic Sr2Sn were considered, and vice versa, hypothetical orthorhombic Mg2Si and cubic Sr2Sn. We found that in all studied cases there is rearrangement of electronic bands, mostly conduction ones, with the change of volume of the cell. In all cases it may leads to the increase of power factor.