Benchmarking Swaths of Intermolecular Interaction Components with Symmetry-Adapted Perturbation Theory

A benchmark database
for interaction energy components of various
noncovalent interactions (NCIs) along their dissociation curve is
one of the essential needs in theoretical chemistry, especially for
the development of force fields and machine-learning methods. We utilize
DFT-SAPT or SAPT(DFT) as one of the most accurate methods to generate
an extensive stock of the energy components, including dispersion
energies extrapolated to the complete basis set limit (CBS). Precise
analyses of the created data, and benchmarking the total interaction
energies against the best available CCSD(T)/CBS values, reveal different
aspects of the methodology and the nature of NCIs. For example, error
cancellation effects between the S2 approximation
and nonexact xc-potentials occur, and large charge transfer energies
in some systems, including heavy atoms, can explain the lower accuracy
of DFT-SAPT. This method is perfect for neutral complexes containing
light nonmetals, while other systems with heavier atoms should be
treated carefully. In the last part, a representative data set for
all NCIs is extracted from the original data.