Lattice dynamics of thallium iodide

Abstract

The long-wavelength optical phonons in orthorhombic TlI are calculated employing a shell model and transferring the potential parameters from cubic TlI and TlBr. Satisfactory agreement between experimental Raman and infrared phonons suggests that the change in the crystal structure alone is the main reason for the redistribution of phonons in the cubic to orthorhombic transition.