Metallization And Superconductivity In Potassium-Doped Methane

Metallization of methane (CH4) has always been an interesting issue. Here, we report a study on the structure, metallization and superconductivity in K-doped CH4 under pressure, based on the particle swarm optimization, density functional theory, and density functional perturbation theory. Summarizing the thermodynamical and dynamical stabilities, the electronic band structures, and the electron-phonon interaction calculations, we predicted that K-doped CH4 in P2(1)/m space-group is a metal and a possible superconductor in the pressure range of 70 - 90 GPa. The superconducting critical temperature is about 12.7 K at 80 GPa. It was found that the charge transfer from K to CH4 drives the metallization and mainly contributes to the electron-phonon interaction. The result confirms that CH4 can become a metal and superconductor under the electron doping and the relative low pressure.