A novel stable hydrogen-rich SnH8 under high pressure

摘要

A first-principles calculation is applied to perform a comprehensive study of the Sn-H system. Besides the common tetravalent hydride, a novel SnH8 crystal with the space group I (4) over bar m2 is reported with the most dominant enthalpy from structure searching techniques. All the H atoms of SnH8 are in the form of H-2 or H-3 units with electrons localized around them, showing covalent bond character. The rich and multiple Fermi surface distribution displays a metallic feature. Further electron-phonon coupling calculations reveal the high T-c of 63-72 K at 250 GPa.