How the narrow DOS peak emerges in H3S superconductor*

The sulfur superhydride H3S is a milestone system for high pressure research, as it ignited a surge of studies for finding high-temperature hydride superconductors under extreme pressure. The prominent feature of this system from theoretical point of view is narrow peak in the density of states at the Fermi level, which has been found by the first-principle calculations. Considering this feature several simulations successfully reproduced the observed high Tc along with the Eliashberg theory for phonon-mediated superconductivity. However, why such peak occurs has eluded simple explanation. Several attempts are actually made to build tight-binding models that reproduce the electronic structure, though they commonly required many tight-binding parameters. Here we report a successful modeling based on an opposite view: nearly uniform electron model (see Ref.). The linearly extended van Hove singularity as the origin of the DOS peak is consistently explained with very few model parameters, which solves the DOS-concentration mechanism underlying the high-Tc superconductivity.