Modelling trapping sites of (HF) 2 in argon clusters

Abstract

Molecular dynamics simulations have been performed for (HF) 2 · Ar 62 heteroclusters to compare the structural and dynamical properties of (HF) 2 in different argon environments. Several minimum energy arrangements which mimic different trapping sites of (HF) 2 in argon related to the matrix isolation and cluster adsorption experimental conditions have been analysed. The potential energy surface of the system has been constructed as a superposition of diatomics-in-molecules potentials for all ArHF triangles, the Quack-Suhm SQSBDE potential for (HF) 2 and pairwise ArAr interaction potentials. Of special interest is a comparison of the configuration in the centre of argon shells and those on the surface of argon clusters. Argon-induced vibrational shifts in (HF) 2 with respect to the naked hydrogen fluoride dimer have been computed for each trapping site. The experimental difference in the HF stretch frequency shifts for (HF) 2 in the matrix and on the surface of argon clusters is precisely reproduced.