MOLECULAR-MODEL OF LATTICE-VIBRATIONS IN ZN3P2

Optical lattice vibrations in Zn3P2 crystals were investigated by refl ectance measurements in the far infrared region (40-400 cm(-1)) and Ra man scattering spectroscopy in the 25-500 cm(-1) region. A series of t ransitions was observed. Their identification was done on the basis of the factor group approach and the normal coordinate analysis. A molec ular model was applied to simplify the calculations. The 40-atom unit cell of Zn3P2 was substituted by an 18-atom molecule. The Urey-Bradley force field model and potential energy distribution were applied in t he phonon calculations. (C) 1998 Elsevier Science B.V. All rights rese rved.