Phase transition and superconductivity in ReS₂, ReSe₂ and ReTe₂

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.