Hybrid density functional methods such as B3LYP and PBE0 have been widely successful but often fail for systems with strong static correlation or significant self-interaction errors. In this work, Prof. Xin Xu’s group introduces a cross-entropy corrected hybrid multiconfiguration pair-density functional theory (HMC-PDFT), in which a cross-entropy term is used to approximate the wavefunction-based correlation energy and to balance static and dynamic correlation effects within a B3LYP-like hybridization scheme. The resulting functional, termed tB4LYP, consistently improves upon conventional MC-PDFT and its linear hybrid variants, achieving accuracy comparable to or better than CASPT2 for a broad range of molecular properties, including bond dissociation energies, ionization potentials, electron affinities, and isomerization energies, while maintaining a much lower computational cost. Notably, tB4LYP provides a highly accurate description of the challenging Cr₂ ground-state dissociation curve and low-lying vibrational levels, demonstrating its robustness for strongly correlated systems and establishing it as an efficient alternative to traditional multireference perturbation methods
Nat. Commun. 16, 235 (2025)
DOI: doi.org/10.1038/s41467-024-55524-z
