High-pressure crystal structures and superconductivity of Stannane (SnH4)
Guoying Gao1, Artem R Oganov, Peifang Li
1National Laboratory of Superhard Materials, Jilin University, Changchun 130012, PR China.
Abstract:
There is great interest in the exploration of hydrogen-rich compounds upon strong compression where they can become superconductors. Stannane (SnH(4)) has been proposed to be a potential high-temperature superconductor under pressure, but its high-pressure crystal structures, fundamental for the understanding of superconductivity, remain unsolved. Using an ab initio evolutionary algorithm for crystal structure prediction, we propose the existence of two unique high-pressure metallic phases having space groups Ama2 and P6(3)/mmc, which both contain hexagonal layers of Sn atoms and semimolecular (perhydride) H(2) units. Enthalpy calculations reveal that the Ama2 and P6(3)/mmc structures are stable at 96-180 GPa and above 180 GPa, respectively, while below 96 GPa SnH(4) is unstable with respect to elemental decomposition. The application of the Allen-Dynes modified McMillan equation reveals high superconducting temperatures of 15-22 K for the Ama2 phase at 120 GPa and 52-62 K for the P6(3)/mmc phase at 200 GPa.
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