Phase transitions and superconductivity in ternary hydride Li2SiH6 at high pressures

We predicted a new ternary hydride Li2SiH6 at high pressures. A systematic structure search in the Li2SiH6 compound reveals novel stable phases with intriguing electronic and phonon properties. It is found that Li2SiH6 is dynamically stable from ambient pressure up to 400 GPa with three novel phases: P312, P 3 over bar , and P 6 over bar 2m. The calculation of electron-phonon coupling combined with Bardeen-Cooper-Schrieffer's argument indicates that this compound may be a candidate for high T-c superconductors under high pressures. In particular, the maximum T-c of P 6 over bar 2 m-Li2SiH6 at 400 GPa reaches 56 K. Our findings further promoted the research on the superconductivity of hydrogen-rich compounds.