Lattice dynamics of wurtzite-type crystals

To deal with the lattice dynamics of wurtzite-type crystals, we have applied the polarizable-ion model following Born and Huang. On the basis of this we have calculated from macroscopic quantities the microscopic ones, namely the effective ionic charges and the electronic polarizabilities. Their values have led to the following relations: the anisotropy of the effective ionic charge has a regular correspondence with the structural anisotropy, and the electronic polarizability increases regularly with increasing unit-cell volume.