Superconducting high-pressure phases of disilane

High-pressure structures of disilane ([Si.sub.2][H.sub.6]) are investigated extensively by means of first-principles density functional theory and a random structure-searching method. Three metallic structures with P-1, Pm-3m, and C2/c symmetries are found, which are more stable than those of [XY.sub.3]-type candidates under high pressure. Enthalpy calculations suggest a remarkably wide decomposition (Si and [H.sub.2]) pressure range below 135 GPa, above which three metallic structures are stable. Perturbative linear-response calculations for Pm-3m disilane at 275 GPa show a large electron-phonon coupling parameter [lambda] of 1.397 and the resulting superconducting critical temperature beyond the order of [10.sup.2] K. metallization | new phase | solid disilane doi/ 10.1073/pnas.1005242107