Superconductivity of lithium-doped hydrogen under high pressure

The high-pressure lattice dynamics and superconductivity of newly proposed lithium hydrides (LiH₂, LiH₆ and LiH₈) have been extensively studied using density functional theory. The application of the Allen-Dynes modified McMillan equation and electron-phonon coupling calculations show that LiH₆ and LiH₈ are superconductors with critical temperatures (T_c) of 38 K at 150 GPa for LiH₆ and 31 K at 100 GPa for LiH₈, while LiH₂ is not a superconductor. The T_c of LiH₆ increases rapidly with pressure and reaches 82 K at 300 GPa due to enhancement of the electron-phonon coupling and the increased density of states at the Fermi level, while the T_c of LiH₈ remains almost constant.