First principles study of Ca2PtO4 in K2NiF4 and ‘post-K2NiF4’ type structures

Deriving the energy-volume equations of state EOS for Ca2PtO4 in Ca2IrO4-type and in K2NiF4-type (knf) structures, leads to energy destabilization at a larger volume for the latter and to propose the former as a post-K2NiF4–pknf–occurring at high pressures with a reduced dimensionality 2D-knf → 1D-pknf and a rearrangement of the PtO6 octahedra from corner sharing in knf to edge sharing in pknf. Bader charge analysis indicates an increased covalence of Pt–O bond with such a transformation. The lowered dimensionality is also illustrated from the density of states.