The mystery of abnormally large volume of PbCrO3 with a structurally consistent Hubbard U from first-principles

Abstract

PbCrO3 is found experimentally to be a cubic perovskite with an abnormally large lattice constant of about 4.00 A. To date, no successful first principle calculations have been carried out for cubic PbCrO3 perovskite. Combining the generalized-gradient approximations and a structurally consistent Hubbard U approach, the crystal, electronic and magnetic structures of PbCrO3 are calculated to explore the mystery of abnormally large volume of PbCrO3 in cubic structure. The crystal structure, magnetic order and half-metallic properties of PbCrO3 are determined. For the first time, a structurally consistent Hubbard U eff of about 8.28 eV for PbCrO3 is calculated based on linear-response approach. With the structurally consistent U obtained by first principles, a \(Pm\bar 3m\) cubic structure with a lattice constant of about 3.98 A for PbCrO3 is obtained successfully. Moreover PbCrO3 is found to be half-metallic ferromagnet with an integral magnet moment of 2.00μ B per unit cell. The anomalously large volume of PbCrO3 in cubic structure results from the strongly correlated electron interaction. The results obtained agree well with experimental data.