Abstract
Intermolecular interactions play a significant roles in the fields of physics, chemistry and biology. The study of intermolecular interactions is a useful step toward gaining a basic understanding of the dynamic behavior of molecules in various environments. Today's quantum chemical calculations are very powerful tools to investigate intermolecular interactions. In the present study, we first investigated the effect of the method of quantum chemical calculations, the selection of basis set and the BSSE (Basis set superposition error) on calculated interaction energies of Ar2 and Ar-NH3 Van der Waals dimers. Second, we carried out quantum chemical calculations to study the structure and stability of Ar2-NH3 Van der Waals trimer and to clarify the nature of molecular interactions. The most stable structure of Ar2-NH3 was found; it can be described by assuming the pairwise additivity of the interaction energies.
