TiC lattice dynamics from ab initio calculations

TL;DR

This paper uses ab initio calculations to derive phonon dispersion and density of states for TiC, showing good agreement with experimental data and revealing distinct vibrational behaviors of Ti and C atoms.

Contribution

It provides a detailed ab initio analysis of TiC lattice dynamics, including phonon dispersion, density of states, and elastic constants, with comparison to experimental results.

Findings

Phonon dispersion curves match neutron scattering data.

Ti atoms contribute to acoustic phonons, C atoms to optical phonons.

Elastic constants are consistent with phonon slope calculations.

Abstract

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 experimental neutron scattering data. The force constants have been determined from the Hellmann-Feynman forces induced by atomic displacements in the 2x2x2 supercell. The calculated phonon density of states suggests that vibrations 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 phonon slopes.