Band structure and Van Hove singularities in H3S

We study the hopping-resolved contribution of the tight-binding parameters to the Van Hove singularities of H3S in the Im-3m cubic structure at 180 GPa close to the Fermi level. By means of a 7×7 tight-binding model, we study the sensitivity of the DOS close to the Fermi level to a change in the tight-binding parameters. We show that the most relevant parameter affecting the DOS at the Fermi level is the direct Wsp? hopping between the 3s and the 3p orbitals of S. In this way, we can understand some peculiar features of H3S and also give some suggestion for enhancing Tc.