Computation of charge-transfer coupling energy with a nonempirically
tuned range-separated density functional is examined. The results
are assessed by comparing with the high-level ab initio benchmark
data sets, HAB11 (
Kubas
Kubas
J. Chem. Phys.2014140104105) of 11 cation radical homodimers and HAB7– (
Kubas
Kubas
Phys. Chem. Chem. Phys.20151714342) of 7 anion radical
homodimers. The mean relative unsigned errors (MRUEs) of the charge-transfer
coupling energy were 3.2% for the HAB11 set and 7.3% for the HAB7–
set. The MRUEs of the exponential decay constant along the face-to-face
intermolecular distance were 2.2% for the HAB11 set and 4.9% for the
HAB7– set. The errors were always smaller than those from the
popular B3LYP functional and, in most cases, smaller than those reported
in previous studies. We also found nearly linear correlations between
the tuned range-separated parameter μ and the energies of highest
occupied and lowest unoccupied orbitals of the monomers and between
1/μ and the number of double bonds in the monomers.