%0 Journal Article %A Kristin Einarsdotter %A Babak Sadigh %A Goran Grimvall %A Vidvuds Ozoliņš %A Kristin A Persson %B Physical Review Letters %D 1997 %G eng %N 11 %P 2073 - 2076 %R 10.1103/PhysRevLett.79.2073 %T Phonon Instabilities in fcc and bcc Tungsten %V 79 %8 09/1007 %! Phys. Rev. Lett. %X

The lattice dynamics of bcc and fcc W is studied as a function of pressure using the density-functional linear-response theory. At high pressures and $T = 0$ K, bcc W has a higher enthalpy than the fcc and hcp phases and it develops phonon softening anomalies related to this thermodynamic instability; however, it remains dynamically stable. In contrast, the widely unstable shear modes of fcc W at zero pressure (when $H_{W}^{fcc} > H_{W}^{bcc}$ ) stabilize with increasing pressure before $H_{W}^{fcc} < H_{W}^{bcc}$ . Hence the thermodynamic and dynamic instabilities are uncorrelated.