Pressure and temperature effects on the Gamma, N and L-phonons in zirconium

The effective potentials for the E-2g-phonon at the Gamma point of the Bril louin zone of hcp Zr, the transverse N- and longitudinal L-phonons of bce Z r are calculated for different pressures by the "frozen phonon" method. The temperature and pressure dependences of the phonon frequencies are studied within the framework of a modified pseudo-harmonic approximation. The resu lts obtained are in good agreement with the experimental ones. The stabilit y of the hcp, bce and w phases of zirconium at different temperatures and p ressures is discussed.