Structural transitions in a classical two-dimensional molecule system

The ground state of a classical two-dimensional (2D) system with a finite number of charge particles, trapped by two positive impurity charges localized at a distance (z0) from the 2D plane and separated from each other by a distance xp are obtained. The impurities are allowed to carry more than one positive charge. This classical system can form a 2D-like classical molecule that exhibits structural transitions and spontaneous symmetry breaking as function of the separation between the positive charges before it transforms into two 2D-like classical atoms. We also observe structural transitions as a function of the dielectric constant of the substrate which supports the charged particles, in addition to broken symmetry states and unbinding of particles.