Pressure-induced polymorphism in CuCl: An ab initio study

We report the results of pseudopotential and full-potential linear augmented-plane-wave (FP-LAPW) calculations on high-pressure phase of copper chloride. It is found that nonlocal ionic pseudopotentials accuracy describe the bonding in these strongly hybridized compounds over a wide range of densities. Successive transitions from CuCl-II (zinc-blende) to CuCl-IV (binary analogue of the metastable BC8 structure found in Si and Ge) and then to CuCl-V (rocksalt) are predicted by both ab initio methods. Both these transitions have been observed in recent neutron power diffraction experiments. The structural properties and electronic energy band structure of zinc blende and NaCl structure CuCl as determined by the psseudopotential and FP-LAPW methods are compared and the band structure of CuCl-IV is reported.