"Best" Iterative Coupled-Cluster Triples Model? More Evidence for 3CC.

To follow up on the unexpectedly good performance of several coupled-cluster models with approximate inclusion of 3-body clusters [Rishi, V.; Valeev, E. F.

Explicitly correlated renormalized second-order Green's function for accurate ionization potentials of closed-shell molecules.

We present an energy-dependent explicitly correlated (F12) formalism for the nondiagonal renormalized second-order (NR2) Green's function method of closed-shell molecules. For a test set of 21 small molecules, the mean basis set error in IP computed using NR2-F12 with aug-cc-pVTZ basis is 0.028 eV, compared to 0.