Phase transition and superconductivity in ReS, ReSe and ReTe.

Transition metal dichalcogenides have attracted significant attention due to both fundamental interest and their potential applications. Here, we have systematically explored the crystal structures of ReX2 (X = S, Se, and Te) over the pressure range of 0-300 GPa, employing swarm-intelligence-based structure prediction methodology. Several new structures are found to be stable at high pressures. The calculated enthalpy of formation suggested that all predicted high-pressure structures are stable against decomposition into elemental end-members. Moreover, we found that the simulated X-ray diffraction patterns of ReSe2 are in good agreement with experimental data. Pressure-induced metallization of ReX2 has been revealed from the analysis of its electronic structure. Our electron-phonon coupling calculations indicate ReSe2 and ReTe2 are superconducting phases at high pressures.