Amplitude instability, phase transitions, and dynamic properties in two-dimensional Yukawa clusters.

Abstract

The conditions for the amplitude instability onset in a two-dimensional Yukawa cluster system consisting of seven particles are investigated for the case of sufficiently large thermal particle displacements. We consider here an analytical approach to derive the criterion for such instability onset, which is based on searching an energetically favorable inflection point of the system potential energy. We show that there is a proportionality between melting curve for an "infinite" two-dimensional system with the hexagonal lattice and analytical curve of critical points for the seven-particle Yukawa cluster. We use numerical simulations to study the structural and dynamical properties of the system near the critical point of the amplitude instability. The obtained results are compared to the criteria for melting of the "infinite" two-dimensional system.