Pressure increase of the electron-phonon interaction in superconducting hexagonal silicon

Using an ab initio pseudopotential approach, the pressure dependence of the electron-phonon interaction parameter λ and the phonon frequencies for metallic hexagonal phases of silicon is calculated. With changing pressure λ is found to go first through a minimum and then reach its maximum value near the phase transition from simple hexagonal (sh) to hexagonal close packed (hcp). At this point the superconducting transition temperature Tc is expected to be above 10 K. In the hcp phase Si is predicted to be superconducting with Tc in the same range as in the sh phase.