Ab Initio Extended Hartree–Fock plus Dispersion Method Applied to Dimers with Hundreds of Atoms

The
Hartree–Fock plus dispersion plus first-order correlation
(HFDc(1)) method consists in augmenting the HF interaction
energy by the correlation part of the first-order interaction energy
and the second-order dispersion and exchange-dispersion energies.
All of the augmentation terms are computed using the symmetry-adapted
perturbation theory based on density functional theory description
of monomers [SAPT­(DFT)]; thus, HFDc(1) is a fully ab initio
method. A partly empirical version of this method, HFDasc(1), uses a damped asymptotic expansion for the dispersion
plus exchange-dispersion term fitted to SAPT­(DFT) ab initio values.
The HFDc(1) interaction energies for dimers in the S22,
S66, S66x8, NCCE31, IonHB, and UD-ARL benchmark data sets are more
accurate than those given by most ab initio methods with comparable
costs. HFDc(1) can be used routinely for dimers with nearly
200 atoms, such as included in the S12L benchmark set, giving results
comparable to those obtained by the most expensive methods applicable.