TY - DATA T1 - Benchmarking the completely renormalised equation-of-motion coupled-cluster approaches for vertical excitation energies PY - 2015/10/15 AU - Piotr Piecuch AU - Jared A. Hansen AU - Adeayo O. Ajala UR - https://tandf.figshare.com/articles/journal_contribution/Benchmarking_the_completely_renormalised_equation_of_motion_coupled_cluster_approaches_for_vertical_excitation_energies/1568589 DO - 10.6084/m9.figshare.1568589 L4 - https://ndownloader.figshare.com/files/2350561 KW - equation-of-motion coupled-cluster methods KW - completely renormalised approaches KW - non-iterative triples corrections KW - electronically excited states KW - benchmarking quantum chemistry methods N2 - The vertical excitation energies for a comprehensive test set of about 150 singlet excited states of 28 medium-sized organic molecules computed using two variants of the completely renormalised (CR) equation-of-motion (EOM) coupled-cluster (CC) method with singles, doubles, and non-iterative triples, abbreviated as δ-CR-EOMCCSD(T), and the analogous two variants of the newer, left-eigenstate δ-CR-EOMCC(2,3) approach are benchmarked against the previously published CASPT2, CC3, and EOMCCSDT-3 results, as well as the suggested theoretical best estimate (TBE) values. The δ-CR-EOMCC approaches are also used to identify and characterise about 50 additional excited states, including several states having substantial two-electron excitation components, which have not been found in the previous work and which can be used in future benchmark studies. It is demonstrated that the non-iterative triples corrections to the EOMCCSD excitation energies defining the relatively inexpensive, single-reference, black-box δ-CR-EOMCC approaches provide significant improvements in the EOMCCSD data, while closely matching the results of the iterative and considerably more expensive CC3 and EOMCCSDT-3 calculations and their CASPT2 and TBE counterparts. It is also shown that the δ-CR-EOMCC methods, especially δ-CR-EOMCC(2,3), are capable of bringing the results of the CC3 and EOMCCSDT-3 calculations to a closer agreement with the CASPT2 and TBE data, demonstrating the utility of the cost-effective δ-CR-EOMCC methods in applications involving molecular electronic spectra. We show that there may exist a relationship between the magnitude of the triples corrections defining δ-CR-EOMCC approaches and the reduced excitation level diagnostic resulting from EOMCCSD. ER -