Structural phase transitions of the metal oxide perovskites SrTiO_3, LaAlO_3, and LaTiO_3 studied with a screened hybrid functional

摘要

We have investigated the structural phase transitions of the transition metal oxide perovskites SrTiO_3, LaAlO3, and LaTiO_3 using the screened hybrid density functional of Heyd, Scuseria, and Ernzerhof (HSE06). We show that HSE06-computed lattice parameters, octahedral tilts, and rotations, as well as electronic properties, are significantly improved over semilocal functionals. We predict the crystal-field splitting (Δ_(Cf)) resulting from the structural phase transition in SrTiO_3 and LaAlO_3 to be 3 meV and 10 meV, respectively, in excellent agreement with experimental results. HSE06 identifies correctly LaTiO_3 in the magnetic states as a Mott insulator. Also, it predicts that the GdFeO_3-type distortion in nonmagnetic LaTiO_3 will induce a large A_(Cf) of 410 meV. This large crystal-field splitting associated with the large magnetic moment found in the G-type antiferromagnetic state suggests that LaTiC>3 has an induced orbital order, which is confirmed by the visualization of the highest occupied orbitals. These results strongly indicate that HSE06 is capable of efficiently and accurately modeling perovskite oxides and promises to efficiently capture the physics at their heterointerfaces.