Full-potential calculations using the generalized-gradient corrections: structural properties of Ti, Zr and Hf under compression

The equilibrium volumes and cohesive energies of Ti, Zr and Hf have been calculated using a full-potential (FP) linear-muffin-tin-orbitals (LMTO) method and the generalized-gradient approximation of Perdew and Wang. A structural phase stability analysis between hcp, ω and bcc structures shows a similar crystal structure sequence with increasing pressure for the three metals. More particularly, the gradient-corrected FP LMTO results for transition volumes as well as for transition pressures are found to be superior to the corresponding local-density approximation results in the three metals.