Abstract
We study the lattice statics and dynamics of Si near the phase transitions. The pressure at and the order of the phase transitions can be determined precisely from the dynamical rather than the static properties. We also present an interpretation of measured Raman frequencies of a high-pressure structure of silicon correcting a previous assignment to the -tin phase, since the phase was unknown. With the new assignment, the ab initio phonon frequencies display an excellent agreement with the experimental data. The transition is accompanied by soft modes which should be accessible in future experiments. The phonon-dispersion curves and density of states point at irregularities of the behavior of the superconducting temperature as a function of the pressure for these phases.
- Received 14 December 2005
DOI:https://doi.org/10.1103/PhysRevB.73.014117
©2006 American Physical Society