Structural, elastic, and high-pressure properties of cubic TiC, TiN, and TiO

We have studied the structural and elastic properties of TiC, TiN, and TiO by means of accurate first principles total-energy calculations using the full potential linear muffin-tin orbital method. The calculations are based on the density functional theory and we have used the local-density Hedin-Lundqvist parametrization as well as the generalized gradient approximation proposed by Perdew and Wang for the exchange and correlation potential. The calculated values for the equilibrium volume, bulk modulus, and elastic constants are generally in very good agreement with experiments. At elevated pressures all these compounds are predicted to undergo a structural phase transition from the relatively open NaCl structure into the more dense CsCl atomic arrangement. The predicted transition pressure for TiO can be reached in modern high-pressure laboratories.