Superconducting high-pressure phases of disilane

Abstract

High-pressure structures of disilane (Si₂H₆) 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 XY₃-type candidates under high pressure. Enthalpy calculations suggest a remarkably wide decomposition (Si and H₂) 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 λ of 1.397 and the resulting superconducting critical temperature beyond the order of 10² K.