Accurate computations of the structures and binding energies of the imidazole⋯benzene and pyrrole⋯benzene complexes

- We have computed accurate binding energies of two NH⋯π hydrogen bonds.
- We compare to results from dispersion-corrected density-functional theory.
- A double-hybrid functional with explicit correlation has been proposed.
- First results of explicitly-correlated ring-coupled-cluster theory are presented.
- A double-hybrid functional with random-phase approximation is investigated.

Using explicitly-correlated coupled-cluster theory with single and double excitations, the intermolecular distances and interaction energies of the T-shaped imidazole⋯benzene and pyrrole⋯benzene complexes have been computed in a large augmented correlation-consistent quadruple-zeta basis set, adding also corrections for connected triple excitations and remaining basis-set-superposition errors. The results of these computations are used to assess other methods such as Møller-Plesset perturbation theory (MP2), spin-component-scaled MP2 theory, dispersion-weighted MP2 theory, interference-corrected explicitly-correlated MP2 theory, dispersion-corrected double-hybrid density-functional theory (DFT), DFT-based symmetry-adapted perturbation theory, the random-phase approximation, explicitly-correlated ring-coupled-cluster-doubles theory, and double-hybrid DFT with a correlation energy computed in the random-phase approximation.