Abstract
Ab initio molecular dynamics simulations are used to solve the long-standing problem of calculating the free energies of unstable phases, such as fcc W. We find that fcc W is mechanically unstable with respect to long-wavelength shear at all temperatures considered (), while the short-wavelength phonon modes are anharmonically stabilized. The calculated fcc-bcc enthalpy and entropy differences at (308 meV and per atom, respectively) agree well with the recent values derived from analysis of experimental data.
- Received 17 October 2008
DOI:https://doi.org/10.1103/PhysRevLett.102.065702
©2009 American Physical Society