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

We use a tight-binding total-energy method, with parameters determined from a fit to first-principles calculations, to examine the newly discovered gamma phase of titanium. Our parameters were adjusted to accurately describe the alphaTi-omegaTi phase transition, which is misplaced by density-functional calculations. We find a transition from omegaTi to gammaTi 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 omegaTi-gammaTi phase transition, but will instead predict a transition from omegaTi to the bcc betaTi phase.