Highly accurate benchmark calculations of the interaction energies in the complexes C6H6•••C6X6 (X = F, Cl, Br, and I)

Different from the case of the benzene dimer, the differences between the interaction energies are always less than 0.50 kcal/mol for face-to-face eclipsed, face-to-face staggered, and paralleldisplaced configurations of all investigated complexes C6H6 center dot center dot center dot C6X6 (X = F, Cl, Br, and I). Hence, it is a great challenge for quantum chemists to accurately calculate the interaction energies for the three configurations of the complexes C6H6 center dot center dot center dot C6X6. This work demonstrates that results obtained with the PBE0 density functional combined with the D3 dispersion correction (PBE0-D3) and the basis set def2-TZVPP are in excellent agreement with the estimates of the coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] complete basis set (CBS) limit. The other finding in this study is that, in comparison with the gold-standard CCSD(T)/CBS benchmark, the spin-component scaled (SCS) zeroth-order symmetry-adapted perturbation theory (SAPT0), when paired with the basis set aug-cc-pVDZ, performs also very well, and its performance is even better than that of the PBE0-D3/def2-TZVPP method or the conventional SAPT/aug-cc-pVQZ method. The findings of this study are very significant because both PBE0-D3/def2-TZVPP and SCS-SAPT0/aug-ccpVDZ can deal with the systems with more than 200 atoms.