Binding energies and structures of C+Arn (n = 1-5), clusters from first principles

We report the minimum energy geometries, binding energies and vibrational spectra of the C+Arn (n = 1-5), clusters which were recently recorded in a time-of-flight mass spectrometer. The C+Ar3 cluster has a planar structure with two long and one short C-Ar bonds while the C+Ar4 cluster forms a square of D-4h symmetry with the carbon atom in the center. The observed drop in the incremental binding energy for the successive Ar atom addition from n = 2 to n = 3 and from n = 4 to n = 5 justifies the classification of the n = 2 and 4 as magic number clusters in the experimental mass spectrum. (C) 1998 Elsevier Science B.V. All rights reserved.