Pressure effect on the transverse Gamma-point optical phonon in hcp Zr

The effective potential for the E-2g phonon at the Gamma point of the Brill ouin zone of Zr is calculated for different pressures by the frozen-phonon method. The temperature and pressure dependences of the phonon frequency ar e studied within the framework of a modified pseudoharmonic approximation. The obtained room-temperature results are in good agreement with the experi mental ones. The observed change in the behavior of omega(P) with increasin g temperature may be attributed to the peculiarities of the phase diagram o f zirconium. [S0163-1829(98)50348-7].