Classical interacting particles in confinement

The lowest energy configurations of systems with N classical particles interacting repulsively and confined in a parabolic potential are studied using a molecular dynamics method. Three different types of interacting potentials, namely 1/r, 1/r(2) and -1n r, where r is the particle separation, are considered. The lowest energy configurations show a shell structure for these interactions. Results are given for up to 50 particles in the system. For small number of particles, the 1/r and 1/r(2) interactions give similar lowest energy configurations. This implies that theoretical treatments based on the 1/r(2) interaction may be used to give qualitative understanding of systems in which the particles interact via a 1/r potential. For -1n r interaction, results from our calculations are found to be different from those obtained within the Thomson model. (C) 1997 Published by Elsevier Science Ltd.