A CCSD(T) study of the He〮NO molecular complex

Abstract

Calculations at the CCSD(T) level of theory employing the cc-pVTZ, aug-cc-pVTZ and aug-cc-pVQZ basis sets are reported. Both the ²A' and the ²A" states are considered, as well as the two linear structures, He〮NO and He〮ON. The highest level of calculation, CCSD(T)/aug-cc-pVQZ//CCSD(T)/aug-cc-pVTZ, indicates that the global minimum is a skewed T-shaped structure, in agreement with recent CEPA calculations, but in disagreement with MP4 calculations, which concluded that the linear He〮ON isomer was the lowest energy geometry. Although the highest level of theory used here indicates that the ²A' surface is the lower in energy, the ordering of the ²A' and the ²A" surfaces has not yet been firmly established. The interaction energy is calculated to be ~27 cmᐨ1, and estimated as being ~30 cmᐨ1 at the basis set limit.