Revisiting LaMnO3: A density functional theory study

초록

Density functional theory has been widely applied to a variety of realistic materials but often fails to accurately describe the properties of correlated systems. The DFT + U method, which introduces a Hubbard U correction to the DFT, has been instrumental in the study of systems such as transition metal oxides. However, the methodological details of DFT + U and its specific impact on the electronic structure and magnetic properties of correlated systems remain incompletely understood. In this study, using the prototypical transition metal oxide LaMnO3 as an example, we systematically assess the performance of two distinct DFT + U methods: spin-polarized DFT + U (SDFT + U) and spin-unpolarized charge-only DFT + U (CDFT + U). We found that, while the Coulomb U acts similarly in both approaches, the Hund's JH plays a fundamentally different role, particularly in determining the correct magnetic phases. Our investigation demonstrates the active role of JH in the exchange splitting, leading to distinct magnetic ground states based on the different schemes. We further investigate the associated magnetic exchange interactions and compare our results with beyond-DFT methods.

키워드