We present a hybrid density functional valence bond method based on unpaired electron density, called λ-DFVB(U), which is a combination of valence bond self-consistent field (VBSCF) method and Kohn–Sham density functional theory (KS-DFT). In λ-DFVB(U), the double-counting of electron correlation is mitigated by a linear decomposition of the electron-electron interaction using a parameter λ. The parameter λ in λ-DFVB(U) is variable and expanded by an index measuring the degree of multireference character, and the expansion coefficients are optimized according to bond dissociation energies of diatomic molecules. Besides, the correlation energy term <i>E</i><sub>C</sub> in λ-DFVB(U) is not scaled with factor, which is based on the assumption that correlation functionals only cover dynamic correlation and exchange functionals mimic some amount of static correlation. Furthermore, effective spin densities constructed from unpaired density are used to address the symmetry dilemma problem in λ-DFVB(U). The method is applied to test calculations of atomization energies, atomic excitation energies, and reaction barriers. λ-DFVB(U) has a computational cost close to VBSCF, and is shown to be comparably accurate as the multireference perturbation theory.

λ-DFVB(U): A hybrid density functional valence bond method based on unpaired electron density

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.