INFLUENCE OF THE ATOM-ATOM INTERACTION ANISOTROPY ON THE STRUCTURE AND STABILITY OF ARNCL2 CLUSTERS

Global potential energy minima have been characterized for ArnCl2 clus ters (n = 2 to 25) using a simple sum of Ar-Ar and Ar-Cl-2 potentials. We compare the results for a fully anisotropic (double-minimum) Ar-Cl -2 interaction, obtained from scaled high-level ab initio calculations , with those for an approximate (single-minimum) form involving equiva lent isotropic ArCl terms. Many of the global minima, with some intere sting exceptions, can be understood in terms of low lying minima of Ar n+2. In particular, several global minima exhibit unusual six-fold axi al symmetry for the more realistic fully anisotropic form. The approxi mate isotropic potential does not support some global minima which the fully anisotropic form predicts to have high relative stability. The effect of three-body forces between Ar atoms is shown to be generally unimportant. (C) 1998 Elsevier Science B.V. All rights reserved.