Phase transition and superconductivity in ReS2, ReSe2 and ReTe2

Five energetically stable phases of P1̄′, P6₃/mmc, I4₁/amd, I4/mmm and I4/mmm′ were predicted in the ReX₂ family of compounds at high pressures. The coordination environment of a Re atom changes from a ReX₆ octahedron or a trigonal prism to a ReX₈ cuboid coordination with increasing pressure. The high-pressure metallic phases of ReX₂ exhibit superconductivity.