Structure change, layer sliding, and metallization in high-pressure MoS2

Based on ab initio calculations and metadynamics simulations, we predict that the electronic gap of 2H-MoS2, a layered insulator, will close under pressures in excess of 25 to 35 GPa. In the same pressure range, simulations and enthalpy optimization predict a structural transition. Free mutual sliding of layers takes place at this transition, the original 2H(c) stacking changing to a 2H(a) stacking typical of 2H-NbSe2, an event explaining for the first time previously mysterious x-ray diffraction and Raman data. Phonon and electron phonon calculations suggest that pristine MoS2 will remain semimetallic up to very high pressures and is thus unlikely to develop superconductivity as it does upon metal intercalation. DOI: 10.1103/PhysRevB.87.144105