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The assignment of an atom to a particular cluster of atoms is defined dynamically in terms of the power flow to the atom. The definition avoids some of the ambiguities present in structural definitions of cluster membership and enables a precise determination of the time at which evaporation and capture events occur in clusters. The definition is illustrated with molecular dynamics studies of evaporation events in Lennard‐Jones clusters, and comparisons are made with structural definitions.

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Copyright 1991 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in The Journal of Chemical Physics and may be found at


David L. Freeman is from the Department of Chemistry.

J. Xie and J. A. Northby are from the Department of Physics.