Structural transitions in a finite classical two dimensional system

We study the properties of the minimum energy state of a classical two-dimensional (2D) system with a finite number of charged particles, trapped by a positive impurity charge localized at a certain distance (d) from the 2D plane. We allow the impurity to carry more than one positive charge. This simple classical model system exhibits structural transitions, spontaneous symmetry breaking and unbinding of particles during a continuous change of the dielectric constant of the substrate which supports the charged particles. Copyright (C) 1996 Published by Elsevier Science Ltd