Band structure and electron-phonon coupling in H3S: A tight-binding model

We present a robust tight-binding description, based on the Slater-Koster formalism, of the band structure of H3S in the Im (3) over barm structure, stable in the range of pressure P = 180-220 GPa. We show that the interatomic hopping between the 3s and 3p orbitals (and partially between the 3p orbitals themselves) of sulfur is fundamental to capturing the relevant physics associated with the Van Hove singularities close to the Fermi level. Comparing the model so defined with density functional theory calculations we obtain a very good agreement not only of the overall band structure but also of the low-energy states and the Fermi surface properties. The description in terms of Slater-Koster parameters permits us also to evaluate at a microscopic level a hopping-resolved linear electron-lattice coupling which can be employed for further tight-binding analyses also at a local scale.