Structure and Stability of R-NH3(R: He,Ne,Ar)

Abstract

We investigated the structures and stability of two weakly bound complexes Ar/NH3 dimer and Ar2/NH3 trimer using ab initio wavefunctions at correlated levels of theory with a large basis set. For the calculations, correlation consistent basis sets of Dunning (aug-cc-pVTZ) were used. The basis set superposition errors (BSSE) were estimated by counterpoise method. All calculations were performed with the Gaussian94 and Gaussian98 program system. For the Ar/NH3 diemer, potential energy surface exibits two minima, which have the argon atom in an equatorial location. One of the two minima is the global minimum ,which has the argon atom in the half plane that contains both the C3 axis of NH3 molecule and is between two hydrogen atoms. The other is the local minimum, which has the argon atom in the half plane that contains both the C3 axis of NH3 molecule and the hydrogen atom closest to the argon atom. The two maxima in the potential energy surface have the argon atom in the axial location. For the Ar2/NH3 trimer, our calculation suggests that the structure resembles T-shaped and Ar2 is closest to the three hydrogen atoms of NH3.