Molecular DFT+U: A Transferable, Low-Cost Approach to Eliminate Delocalization Error

• DOI: 10.48550/arxiv.2103.06781
• Publication Date: 2021-01-01
• Authors: Akash Bajaj; Heather J. Kulik
• Keywords: Chemical Sciences not elsewhere classified; transition-metal chemistry; FOS: Physical sciences; ligand orbitals; DFT; 01 natural sciences; error-reducing effect; DE; Sociology; alternative valence-state; Physics - Chemical Physics; 0103 physical sciences; energy penalty; Low-Cost Approach; Chemical Physics (physics.chem-ph); Condensed Matter - Materials Science; Ecology; transition-metal complexes; Materials Science (cond-mat.mtrl-sci); electron configurations; integer occupations; 541; MO; AO; Medicine; representative transition-metal com.; ligand field strengths; Delocalization Error; Biological Sciences not elsewhere classified

While density functional theory (DFT) is widely applied for its combination of cost and accuracy, corrections (e.g., DFT+U) that improve it are often needed to tackle correlated transition-metal chemistry. In principle, the form DFT+U, consisting a set localized atomic orbitals (AO) quadratic energy penalty deviation from integer occupations those AOs, enables recovery exact conditions piecewise linearity derivative discontinuity. Nevertheless, practical complexes, where both states ligand participate in bonding, standard DFT+U can fail eliminate delocalization error (DE). Here, we show by introducing an alternative valence-state (i.e., molecular orbital or MO) basis approach, recover cases have no error-reducing effect. This MO-based also eliminates DE AO-based already successful. We demonstrate transferability our approach on range field strengths H_2O CO), electron configurations Sc Fe Zn), spin low-spin high-spin) representative complexes.