First-principles study of superconductivity in the hole self-doped LiB1.1C0.9

Abstract

Electronic density of states of LiBC, electronic band structure, lattice dynamics, and superconducting properties for hypothetical LiB1.1C0.9 are obtained by first-principles calculations within the virtual-crystal approximation treatment. It is found that the top of the valence band of LiBC are mainly due to the C 2p states, with sizable contributions of B 2p states and very small contributions from Li states. We thus suggest that the slight hole doping of LiBC through partial substitution of B or C atoms may more easily metallize LiBC than that of the removal of Li atoms from LiBC. For example, the partial substitution of C by B atoms can produce an insulator-metal transition and develop superconductivity. To assess the thermodynamic stability of LiB1+xC1−x, the formation energy is calculated using the supercell method. For LiB1.1C0.9, the obtained formation energy is −9.4 eV, indicating that it is energetically favorable. The electron-phonon coupling constant λ for LiB1.1C0.9 is 0.75, and superconducti...