Modeling many-body dispersion interactions for rare-earth halide perovskites

Rare-earth halide perovskites (REHP) have gained increasing attention due to their unique structures and properties. However, their accurate study poses a significant challenge from both theoretical and experimental point of view. Here, we investigate the structural, electronic and thermodynamic properties of RE-based perovskites (CsREI₃, RE = La, Eu and Yb) using first-principles density-functional theory approaches. In particular, we employ a recently developed many-body dispersion model for bulk systems (MBD-ε) to understand nonlocal van der Waals (vdW) interactions in the perovskite materials. Our results suggest an adequate treatment of screening effects is an effective way of alleviating the overbinding issue observed by broadly employed vdW approaches, highlighting the importance of many-body dispersion interactions in predicting crystal structures. Electronic properties and phonon vibrations are further investigated and care has been taken to capture anharmonicity and spin-orbit coupling (SOC) effects in REHP.