Superconducting behavior in compressed solid SiH4 with a layered structure.

The electronic and lattice dynamical properties of compressed solid SiH4 have been calculated in the pressure range up to 300 GPa with density functional theory. We find two energetically preferred insulating phases with P2(1)/c and Fdd2 symmetries at low pressures. We demonstrate that the Cmca structure having a layered network is the most likely candidate of the metallic phase of SiH4 over a wide pressure range above 60 GPa. The superconducting transition temperature in this layered metallic phase is found to be in the range of 20-75 K.