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We predicted a new ternary hydride Li 2 SiH 6 at high pressures. A systematic structure search in the Li 2 SiH 6 compound reveals novel stable phases with intriguing electronic and phonon properties. It is found that Li 2 SiH 6 is dynamically stable from ambient pressure up to 400 GPa with three novel phases: P312, P 3 ¯ , and P 6 ¯ 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 ¯ 2 m -Li 2 SiH 6 at 400 GPa reaches 56 K. Our findings further promoted the research on the superconductivity of hydrogen-rich compounds. [ABSTRACT FROM AUTHOR]

Hydrogen-based, boron-based, and carbon-based compounds have been the focus of previous investigations in the process of searching for electron–phonon high temperature superconductors. In this paper, the exploration of superconductivity of the hole doping of metal covalent carbon–nitrogen compound MgCN2 within virtual-crystal approximation treatment is proposed based on first-principles calculations. For the hole-doped Mg0.9Li0.1CN2, the electron–phonon coupling strength λ and the superconducting transition temperature T C are predicted to be 0.66 and 14.4 K, respectively. This shows that the metal covalent carbon–nitrogen compound is a potential candidate for electron–phonon superconducting material. [ABSTRACT FROM AUTHOR]