Theoretical analysis of 17–19-atom metal clusters using many-body potentials †

Abstract

A detailed study is presented of the low-energy isomers for 17–19-atom clusters of Al, Ca, Fe, Ni, Pd and Pt, bound by Murrell–Mottram 2 + 3-body potentials, using a Random Search method. A systematic analysis is also made of isomers formed by removing one or two atoms from the double icosahedron M19 cluster geometry. Such “incomplete double icosahedra” are predicted to be the global minima for Pd18, Fe18 and Ca18—although the global minima for Fe18 and Ca18 are different to those previously described. In the cases of Al, Ni and Pt clusters, there are low-lying isomers (or even global minima) which are not derived from the double icosahedron, but rather have four-fold symmetry structures derived from capped Ino decahedra. Comparisons are made between the results obtained for Murrell–Mottram potentials and alternative many-body (Sutton–Chen) and pair (Lennard-Jones and Morse) potentials. Similar structural patterns are observed and differences are found between the various elements for both the Murrell–Mottram and the Sutton–Chen potentials.