First-principles study of electronic structure and superconductivity of PbTa2Se

The existences of topological nodal-line states and topological Dirac surface states in the non-centrosymmetric superconductor PbTaSe2 have been demonstrated by some recent experiments combining with first-principles simulations. Here, we predict by means of the first-principles calculations that PbTa2Se is also a phonon-mediated superconductor. The superconducting temperature Tc is estimated to be ∼7 K, greatly larger than that of PbTaSe2 (Tc ∼ 3.8 K). The main contribution to the electron-phonon coupling and superconductivity is from the in-plane vibrations of Ta atoms. After including the spin-orbit coupling, a continuous energy gap in the whole Brillouin-zone is opened.