Manifestation of electron-phonon interaction in phonon anomaly, superconductivity and transport properties of layered 2H-NbS₂

Role of electron-phonon interaction in physical properties of 2H-NbS₂ is elucidated microscopically. Characteristic mode and wave vector dependences of the electron-phonon interaction cause remarkable frequency renormalization of the Σ₁ phonon modes around q = 2/3ΓM, which consist mainly of the Nb vibrations. The superconducting and the transport spectral functions have significant values only in the low-frequency range (ω < 20 meV) corresponding to the Nb vibrations. The superconducting transition temperature and the tunneling spectra are obtained by solving the Eliashberg equation. The electrical and thermal resistivities calculated by solving the Boltzmann equation with the use of the transport spectral function agree with observations.