Raman and infrared phonons in tetragonal ZnPand CdPcrystals: a density functional study.

Lattice dynamic properties of the tetragonal modification of ZnPand CdPcrystals (space group P422, no 92) are calculated within the density functional theory. Theoretical results are shown to compare favorably with available Raman scattering and infrared reflection/transmission experimental data, which allows assignment of Raman-and infrared-active modes to the specific lattice eigenmodes. It is confirmed that several distinct features of vibrational spectra of these compounds steam from the presence of four phosphorous spiraling chains within crystallographic unit cell.