What drives relatively high superconducting temperature in bulk 2M-WS₂?

The novel monoclinic phase of tungsten diselenide (2M-WS₂) is a topological superconductor withthe highest critical temperature (T_c ~ 9 K) among all the known superconducting transition metal dichalcogenides at ambient pressure. However, it is still not fully understood what distinguishes this material from other similar materials, resulting in its relatively high T_c. Using first-principles calculations, we show that a unique combination of four factors is mainly responsible for its high T_c: (i) the presence of a sharp peak in the density of states at the Fermi level, (ii) the intra- and inter-band nesting of the Fermi surface, (iii) a relatively large electron-phonon coupling that is enhanced by the low-lying tungsten-derived phonon modes, and (iv) the multiband character of superconductivity. We also identify the reasons why undeformed 2M-WS₂ is close to the top of the superconducting dome.