Low-pressure superconductivity in lithium-doped methane predicted by first principles

To explore the high-temperature superconductor at low pressures, we have investigated the crystal structures, electronic properties, and possible superconductivity in the case of methane (CH4) doped by lithium in the pressure range of 0-100GPa, based on the first-principles calculations. The results show that Li-intercalated CH4 (Li-x(CH4)(1-x)) can realize metallization and superconductivity at low pressures, even 5GPa. We find that there is a charge transfer between Li and CH4, but the metallization is driven by the change of crystal field induce by doping instead of charge transfer. The critical temperture is predicted from 3.8K at 5GPa for LiCH4 to 12.1K at 100GPa for Li(CH4)(4). The low-pressure superconductivity of Li-x(CH4)(1-x) can be further optimized by adjusting component and pressure.