The geometrical structures of M+(Ar)nions, withn=1ndash;14, have been studied by the minimization of a manyhyphen;body potential surface with a simulated annealing procedure. The minimization method is justified for finite systems through the use of an information theory approach. It is carried out for eight potentialhyphen;energy surfaces constructed with twohyphen; and threehyphen;body terms parametrized from experimental data andabinitioresults. The potentials should be representative of clusters of argon atoms with firsthyphen;row transitionhyphen;metal monocations of varying size. The calculated geometries for M+=Co+and V+possess radial shells with small (ca. 4ndash;8) firsthyphen;shell coordination number. The inclusion of an ionhyphen;inducedhyphen;dipolendash;ionhyphen;inducedhyphen;dipole interaction between argon atoms raises the energy and generally lowers the symmetry of the cluster by promoting incomplete shell closure. Rotational constants as well as electric dipole and quadrupole moments are quoted for the Co+(Ar)nand V+(Ar)npredicted structures.
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