Alpha-CrCl2 under pressure: prediction of a metallic phase transition.

The volume-pressure behavior for the alpha-CrCl(2) phase is studied at the density functional level of theory. The calculations predict a metallic phase transition at 15 GPa from a generalized gradient approximation. The addition of an on-site Hubbard repulsion term shifts this transition to 35 GPa. Higher pressure leads to significant changes in the octahedral ligand environment around the Cr atoms, changing from a prolate to oblate environment toward the metallic phase, and the local magnetic moments collapse close to the metallic phase transition.