Screened hybrid functional applied to 3d^0-->3d^8 transition-metal perovskites LaMO3 (M=Sc-Cu): influence of the exchange mixing parameter on the structural, electronic and magnetic properties

摘要

We assess the performance of the Heyd-Scuseria-Ernzerhof (HSE) screenedhybrid density functional scheme applied to the perovskite family LaMO3(M=Sc-Cu) and discuss the role of the mixing parameter alpha (which determinesthe fraction of exact Hartree-Fock exchange included in the density functionaltheory (DFT) exchange-correlation functional) on the structural, electronic,and magnetic properties. The physical complexity of this class of compounds,manifested by the largely varying electronic characters(band/Mott-Hubbard/charge-transfer insulators and metals), magnetic orderings,structural distortions (cooperative Jahn-Teller like instabilities), as well asby the strong competition between localization/delocalization effectsassociated with the gradual filling of the t_2g and e_g orbitals, symbolize acritical and challenging case for theory. Our results indicates that HSE isable to provide a consistent picture of the complex physical scenarioencountered across the LaMO3 series and significantly improve the standard DFTdescription. The only exceptions are the correlated paramagnetic metals LaNiO3and LaCuO3, which are found to be treated better within DFT. By fitting theground state properties with respect to alpha we have constructed a set of'optimum' values of alpha from LaScO3 to LaCuO3: it is found that the 'optimum'mixing parameter decreases with increasing filling of the d manifold (LaScO3:0.25; LaTiO3 & LaVO3: 0.10-0.15; LaCrO3, LaMnO3, and LaFeO3: 0.15; LaCoO3:0.05; LaNiO3 & LaCuO3: 0). This trend can be nicely correlated with themodulation of the screening and dielectric properties across the LaMO3 series,thus providing a physical justification to the empirical fitting procedure.