High-Pressure Phases of Silane

High-pressure phases of silane ${\mathrm{SiH}}_4$ are predicted using first-principles electronic structure methods. We search for low-enthalpy structures by relaxing from randomly chosen initial configurations, a strategy which is demonstrated to work well for unit cells containing up to at least ten atoms. We predict that silane will metallize at higher pressures than previously anticipated but might show high-temperature superconductivity at experimentally accessible pressures.

Figure 1

The enthalpies per ${\mathrm{SiH}}_4$ unit of various structures as a function of pressure, referenced to the $T1$ phase of Ref. 4.

Figure 2

Densities of states of the $I{4}_1/a$ and $C2/c$ phases at the coexistence pressure of 262.5 GPa. The partial density of states projected onto the H atoms is shown by dashed curves and the Fermi energies by the vertical dashed lines.

Figure 3

The $I{4}_1/a$ and $C2/c$ structures. The golden spheres represent silicon atoms, and the white spheres hydrogen.