First-principles calculation of superconductivity in hole-doped LiBC: Tc=65 K -: art. no. 020504

The lattice-dynamical properties of LixBC are calculated for several values of x using density-functional perturbation theory. We find that the electron-phonon coupling parameter lambda increases monotonically with decreasing x to a maximum value of 1.4 for x=0.125, owing to the increasing radius of multiply nested Fermi surface cylinders. The B-C bond-stretching phonon modes have frequencies that are 28% higher than the equivalent modes in MgB2. This combination results in a T-c of about 65 K for x=0.5.