Screened hybrid functional applied to 3d~0 → 3d~8 transition-metal perovskites LaMO_3 (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) screened hybrid density functional scheme applied to the perovskite family LaMO_3 (M = Sc-Cu) and discuss the role of the mixing parameter α [which determines the fraction of exact Hartree-Fock exchange included in the density functional theory (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-transf er insulators and metals), magnetic orderings, structural distortions (cooperative Jahn-Teller-type instabilities), as well as by the strong competition between localization/delocalization effects associated with the gradual filling of the T_(2G) and e_G orbitals, symbolize a critical and challenging case for theory. Our results indicate that HSE is able to provide a consistent picture of the complex physical scenario encountered across the LaMO_3 series and significantly improve the standard DFT description. The only exceptions are the correlated paramagnetic metals LaNiO_3 and LaCuO_3, which are found to be treated better within DFT. By fitting the ground-state properties with respect to a, we have constructed a set of "optimum" values of α from LaScO_3 to LaCuO_3: it is found that the optimum mixing parameter decreases with increasing filling of the d manifold (LaScO_3: 0.25; LaTio_3 and LaVO_3: 0.10-0.15; LaCrO_3, LaMnO_3, and LaFeO_3: 0.15; LaCoO_3: 0.05; LaNiO_3 and LaCuO_3: 0). This trend can be nicely correlated with the modulation of the screening and dielectric properties across the LaMO_3 series, thus providing a physical justification to the empirical fitting procedure. Finally, we show that by using this set of optimum mixing parameter, HSE predict dielectric constants in very good agreement with the experimental ones.