Ground state configurations and melting of two-dimensional non-uniformly charged classical clusters

Abstract

We consider classical two-dimensional (2D) Coulomb clusters consisting of two species containing five particles with charge q(1) and five with charge q(2), respectively. Using Monte Carlo and molecular dynamics (MD) simulations, we investigated the ground state configurations as well as radial and angular displacements of particles as a function of temperature and their dependence on the ratio q = q(2)/q(1). We found new configurations and a new multi-step melting behavior for q sufficiently different from the uniform charge limit q = 1.

Genetic algorithm approach to calculation of geometric configurations of 2D clusters of uniformly charged classical particles

“…The important case of N = 20 is illustrated in Fig. 2 and shows that for the configurations (1, 6,13) and (1,7,12) the energy density U /N difference is extremely tiny and the former corresponds to the ground state. This prediction agrees with experiment [6], whereas the opposite was found in literature [10].…”

“…We expect that these configurations enable an inter-shell rotation of the clusters as the excess energy is lower than that needed for the particle exchange. Finally, we have attempted to search for the metastable states found in the course of melting Coulomb clusters with magic configurations [7]. For these clusters the inter-shell rotation is accompanied by the squeezing of the corresponding shells with finite width.…”

“…This problem is interesting from both theoretical and practical points of view. The model systems have many physical realizations [6,7] and rich dynamics [8]. At zero temperature, the particles are distributed over a number of concentric shells [9][10][11] and their population is hereafter named a configuration.…”

“…The ground-state(1,6,13) and metastable state(1,7,12) configurations for the model with logarithmic interactions and N = 20 particles.…”