TiC lattice dynamics from ab initio calculations

Ab initio calculations and a direct method have been applied to derive the phonon dispersion curves and phonon density of states for the TiC crystal. The results are compared and found to be in a good agreement with the exper imental neutron scattering data. The force constants hat-e been determined from the Hellmann-Feynman forces induced by atomic displacements in a 2 x 2 x 2 supercell. The calculated phonon density of states suggests that vibra tions of Ti atoms form acoustic branches, whereas the motion of C atoms is confined to optic branches. The elastic constants have been found using the deformation method and compared with the results obtained from acoustic ph onon slopes.