Phase transition and elastic constants of zirconium from first-principles calculations

Using the projector augmented wave (PAW) within the Perdew-Burke-Ernzerhof (PBE) form of the generalized gradient approximation (GGA), we investigate the effect of hydrostatic pressure on the structures of zirconium metal at zero temperature. We obtain the omega --> bcc transition at around 26.8 GPa, which is in excellent agreement with the experimental values. We also find that the omega phase is most stable at 0 K and 0 GPa. This conclusion is supported by first-principles calculations of Schell et al and Jona et al. The elastic constants of omega-Zr under high pressures are calculated for the first time. We find that the compressional and shear wave velocities increase monotonically with increasing pressure and the results are in good agreement with the available experimental data. The pressure dependences of three anisotropies of elastic waves are also presented.