High accuracy benchmark calculations on the benzene dimer potential energy surface

Using our new parallel CCSD(T)/QCISD(T) program, we have optimized the geometries of the main conformations and performed potential scans on the benzene dimer at the QCISD(T)/aug-cc-pVTZ level. For each optimized geometry, single point energies were evaluated at the QCISD(T)/aug-cc-pVxZ level, where x = D,T,Q. The largest calculation, QCISD(T)/aug-cc-pVQZ involves 30 correlated orbitals and 1512 basis functions and is thus among the largest coupled cluster type calculations performed to date. The results allow a critical evaluation of MP2-based basis set extrapolation procedures.