CCSDT/aug-cc-pVXZ calculations were performed on the CN, and first row diatomic molecules. The inclusion of diffuse functions improves the dissociation energies of the anionic systems by 2.0–3.4 kcal/mol, which is relevant bearing in mind the goal of achieving chemical accuracy. The contribution of the diffuse functions in the case of neutral (0.6 kcal/mol) is by no means negligible in this context. A serious discrepancy between the theoretical prediction and the experimental values available for the dissociation energy of was found. Since the theoretical deficiences commonly ascribed to the CCSDT method (single-reference and spin contamination when using UHF zeroth-order wave functions) cannot be invoked in this case, further experimental work is required to throw some light on the origin of such a discrepancy. The performance of CCSDT for adiabatic electron affinities is excellent in the case of and For the observed discrepancies can be explained in terms of the well-known multiconfigurational nature of the ground state of the molecule.
Skip Nav Destination
Research Article| February 01 2001
Performance of CCSDT for first row diatomics: Dissociation energies and electron affinities
J. A. Sordo; Performance of CCSDT for first row diatomics: Dissociation energies and electron affinities. J. Chem. Phys. 1 February 2001; 114 (5): 1974–1980. https://doi.org/10.1063/1.1335617
Download citation file: