Molecule-doped rare gas clusters:: structure and stability of ArnNO(X 2Π1/2,3/2), n ≤ 25, from new ab initio potential energy surfaces of ArNO

High level ab initio calculations carried out for the (2)A' and (2)A states of ArNO((XII)-I-2) predict a crossing near the T-shape configuration, with the 2A' minimum being slightly deeper. Spinorbit coupling is included through a model treatment and results in two potential energy surfaces with similar topologies, nearly parallel to each other and close to the averaged non-relativistic surface. These results are used to construct a DIM-like model for ArnNO clusters. The lowest energy cluster structures are found to resemble those for Arn+1 with NO lying in the surface. The set of major magic numbers (structures of pronounced stability) is also the same as for the Arn+1 clusters, and is emphasized further by the detachment of NO, which requires a larger energy than for detachment of a single Ar atom. The relations of the difference between the two dissociation energies and of the ArnNO(1/2 --> 3/2) excitation energy to the magic numbers are discussed.