Ab initio investigation of perovskite and post-perovskite CaPtO3

For the recently synthesized post-perovskite (PPV) CaPtO3 we investigate the electronic band structure properties in connection with hypothetical perovskite PV-CaPtO3 within density functional theory using pseudo-potential and all electron methods. Both systems are found insulating in agreement with a tetravalent Pt(IV) low spin d6 state. The equilibrium values of the volume and energy point to a stabilization of the PPV versus PV oxide with a smaller volume in agreement with other homologue systems within Earth lower mantle such as PPV-MgSiO3. This is also addressed from the analysis of the chemical bonding focusing on the change of the Pt-O bonding upon going from PV and PPV systems whereby the covalent Pt-O bonds are differentiated and reinforced within PPV system with respect to PV.