Phonon-phonon coupling and the stability of the high-temperature bcc phase of Zr

Abstract

Phonon-phonon coupling strengths have been derived from first-principles total energy calculations for bcc Zr. It is shown that the instability leading to the bcc-hcp first-order phase transition in Zr is overcome at high temperatures by the strong interactions between the ${\mathrm{T}}_{1}$ N-point phonon and other low-lying (110) ${\mathrm{T}}_{1}$ vibrational modes.