Tight-binding study of high-pressure phase transitions in titanium: Alpha to omega and beyond

We use a tight-binding total-energy method, with parameters determined from a fit to first-principles calculations, to examine the newly discovered γ phase of titanium. Our parameters were adjusted to accurately describe the αTi-ωTi phase transition, which is misplaced by density-functional calculations. We find a transition from ωTi to γTi at 102 GPa, in good agreement with the experimental value of 116 GPa. Our results suggest that current density-functional calculations will not reproduce the ωTi-γTi phase transition, but will instead predict a transition from ωTi to the bcc βTi phase.