title: Dynamical stability of body center cubic iron at the Earth's core conditions.
abstract: Here, using self-consistent ab initio lattice dynamical calculations that go beyond the quasiharmonic approximation, we show that the high-pressure high-temperature bcc-Fe phase is dynamically stable. In this treatment the temperature-dependent phonon spectra are derived by exciting all the lattice vibrations, in which the phonon-phonon interactions are considered. The high-pressure and high-temperature bcc-Fe phase shows standard bcc-type phonon dispersion curves except for the transverse branch, which is overdamped along the high symmetry direction Gamma-N, at temperatures below 4,500 K. When lowering the temperature down to a critical value T(C), the lattice instability of the bcc structure is reached. The pressure dependence of this critical temperature is studied at conditions relevant for the Earth's core.
authors.affiliation: Condensed Matter Theory Group, Department of Physics, Uppsala University, Box 530, SE-751 21 Uppsala, Sweden. wei.luo@fysik.uu.se
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.forename: Börje
authors.initials: B
authors.lastname: Johansson
authors.forename: Olle
authors.initials: O
authors.lastname: Eriksson
authors.forename: Sergiu
authors.initials: S
authors.lastname: Arapan
authors.forename: Petros
authors.initials: P
authors.lastname: Souvatzis
authors.forename: Mikhail I
authors.initials: MI
authors.lastname: Katsnelson
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ahuja