Investigation of the benzene-dimer potential energy surface: DFT/CCSD(T) correction scheme.

A novel method, designated as the density functional theory/coupled-cluster with single and double and perturbative triple excitation [DFT/CCSD(T)] correction scheme, was developed for precise calculations of weakly interacting sp(2) hydrocarbon molecules and applied to the benzene dimer. The DFT/CCSD(T) interaction energies are in excellent agreement with the estimated CCSD(T)/complete basis set interaction energies. The tilted T-shaped structure having C(s) symmetry was determined to be a global minimum on the benzene-dimer potential energy surface (PES), approximately 0.1 kcal/mol more stable than the parallel-displaced structure. A fully optimized set of ten stationary points on the benzene-dimer PES is proposed for the evaluation of the reliability of methods for the description of weakly interacting systems.