Abstract
We apply a recently introduced method for global optimization to determine the ground state energy and configuration for model metallic clusters. The global minimum for a given N–atom cluster is found by following the damped dynamics of the N particle system on an evolving potential energy surface. In this application, the time dependent interatomic potential interpolates adiabatically between the Lennard–Jones (LJ) and the Sutton–Chen (SC) forms. Starting with an ensemble of initial conditions corresponding to the ground state configuration of the Lennard–Jones cluster, the system asymptotically reaches the ground state of the Sutton–Chen cluster. We describe the method and present results for specific cluster size N = 15, when the ground state symmetry of LJN and SCN differ.
Highlights
Determination of the lowest energy configuration for a cluster of N atoms is a nontrivial task [1, 2, 3, 4, 5]
A point of interest is that for the Sutton-Chen 9-6 family of potentials,[17, 18] the symmetries of the global minimum configurations are frequently different from the symmetries of the Lennard–Jones minima, so that in the adiabatic switching process, the cluster atoms must move so as to adopt a different symmetry
In this paper we have presented the outline of a general procedure for global optimization with specific application to the problem of cluster ground state geometry determination
Summary
Determination of the lowest energy configuration for a cluster of N atoms is a nontrivial task [1, 2, 3, 4, 5]. A case in point is the 38 atom LJ cluster which has the so–called “double funnel” structure; the global minimum, which has octahedral symmetry, is marginally lower than the first excited state which has icosahedral symmetry. These were respectively found by the basin hopping technique [7] and a genetic algorithm method [8, 9]. In the present paper we apply this method to determine the ground state configurations and energies of atomic clusters described by the many–body Sutton–Chen potential [17, 18] by switching. We have learned a lot from him, both in conversation as well as through his many articles and reviews [19]
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