Density Functional Model for Nondynamic and Strong Correlation

摘要

A single-term density functional model for the left right nondynamic/strong electron correlation is presented based on single-determinant Kohn-Sham density functional theory. It is derived from modeling the adiabatic connection for kinetic correlation energy based on physical arguments, with the correlation potential energy based on the Becke'13 model (Becke, A.D. J. Chem. Phys. 2013, 138, 074109). This functional satisfies some known scaling relationships for correlation functionals. The fractional spin error is further reduced substantially with a new density-functional correction. Preliminary tests with self-consistent-field implementation show that the model, with only three empirical parameters, recovers the majority of left right nondynamic/strong correlation upon bond dissociation and performs reasonably well for atomization energies and singlet triplet energy splittings. This study also demonstrates the feasibility of developing DFT functionals for nondynamic and strong correlation within the single-determinant KS scheme.