Eur. Phys. J. D 33, 421-432 (2005)
https://doi.org/10.1140/epjd/e2005-00070-4

Structure and dynamics of cationic van-der-Waals clusters

I. Binding and structure of protonated argon clusters

¹ Universität Potsdam, Institut für Chemie, Karl-Liebknecht-Straße 24-25, 14476 Golm, Germany
² Hahn-Meitner-Institut, Abteilung SF5, Glienicker Straße 100, 14109 Berlin, Germany

Corresponding author: ^a zuelicke@tc1.chem.uni-potsdam.de

Received: 14 February 2005
Published online: 24 May 2005

Abstract

The geometric structure and bonding properties of medium-sized Ar_nH⁺ clusters (n = 2–35), in which a proton is wrapped up in a number of Ar atoms, are investigated by applying a diatomics-in-molecules (DIM) model with ab-initio input data generated by means of multi-reference configuration-interaction (MRCI) computations. For the smaller complexes, n = 2–7, cross-checking calculations employing the coupled-cluster approach (CCSD) with the same one-electron atomic basis set as for the input data calculations (aug-cc-pVTZ from Dunning), show good agreement thus justifying the extension of the DIM study to larger n. Local minima of the multi-dimensional potential-energy surfaces (PES) are determined by combining a Monte-Carlo sampling followed, for each generated point, by a steepest-descent optimization procedure. For the electronic ground state of the Ar_nH⁺ clusters, the global minimum (corresponding to the most stable structure of the cluster) as well as secondary minima are found and analyzed. The structural and energetic data obtained reveal the building-up regularities for the most stable structures and make it possible to formulate a simple increment scheme. The low-lying excited states are also calculated by the DIM approach; they all turn out to be globally repulsive.