2025/08/04 by Lórien MacEnulty, MacEnulty, Lórien, João Paulo Almeida de Mendonça +5
Chemistry · Engineering · Materials Science · #Chemical Physics (physics.chem-ph) #Computational Physics (physics.comp-ph) #FOS: Physical sciences #Magnetism in coordination complexes #Materials Science (cond-mat.mtrl-sci) #Metal-Catalyzed Oxygenation Mechanisms #Organic Light-Emitting Diodes Research #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.2508.01979
openalex publication_date 2025/08/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The effect of the Hund's J terms in various DFT+U+J corrections to semi-local spin-density functional theory is assessed for a series of four octahedrally coordinated Fe(II) spin-crossover molecules spanning the covalent end of the ligand field spectrum. We report values and analyze trends for the Hubbard U and Hund's J parameters determined via minimum-tracking linear response for all valence atomic subspaces and relevant spin states in these molecules. We then methodically apply them via simplified rotationally-invariant Hubbard functionals in search of the simplest combination to yield reliable adiabatic energy differences with respect to those obtained using CASPT2/CC. The observed failure of canonical, positively-signed Hund's J terms in furthering the already robust capacity of DFT+U to obtain accurate energetics prompts an evaluation of their limitations when seeking to account for the static correlation phenomena in such strongly covalent systems and suggests directions for their improvement.