Theoretical Study on the Intermolecular Interaction of Ar/(NH3)2

Abstract

Recently, the experimental detection and characterization of Van der Waals trimers is a subject of growing interest. In the present study, the structures and energies for the Ar-(NH3)2 Van der Waals trimer have been studied at the level of second-order M?ller-Plesset perturbation theory (MP2) using correlation consistent basis sets of Dunning [aug-cc-pVTZ]. For the (NH3)2 dimer, intermolecular potential energy surfaces were calculated at the several gemometries. The most stable structure exibits an asymmetrical geometry, in which a value of 3.24 angstrom is obtained for the N-N distance and the two C3 axes of the NH3 molecules and the N-N axis does not exist in the same plane. For the Ar-(NH3)2 trimer, two stable isomers were located and characterized. The most stable isomer exhibits the structure in which an Ar atom interacts with two NH3 molecules. In the other isomer, an Ar atom interacts only one NH3 molecule. The details of the potential energy surfaces are discussed.