An integral equation approach to an sp3d5liquid: electronic structure of liquid silicon

In order to combine the advantages of tight-binding integral equation methods with basis sets not restricted to the lowest two orbital quantum numbers we extend the molecular fluid approach for the sp3 model of Lomba et al to arbitrarily high orbital quantum numbers. As an example, we present a single-superchain/effective-medium calculation of the electronic density of states for liquid silicon within a tight-binding approximation that includes, besides the 3s and 3p orbitals, also the 3d orbitals. Comparison with results from the sp3 model and different molecular dynamics results shows that within this sp3 d5 model very good agreement with plane-wave calculations is found whereas the sp3 model leads to unsatisfactory results.