The structure and spectrum of the anisotropically confined two-dimensionalYukawa system

We have studied the structural and spectral properties of the classical sys tem consisting of a finite number of charged particles, moving in two dimen sions (2D), and interacting through a screened Coulomb potential and held t ogether by an anisotropic harmonic potential. it is known that for the bare Coulomb interaction, the system crystallizes in well defined ordered confi gurations in which the particles are distributed in shells. However, we hav e found that the occupation of the shells changes considerably as a functio n of the screening parameter, and for large screening, the shell structure disappears and the particles form a Wigner lattice. We have shown that the eigenmodes of the system stiffen with increasing screening. By increasing t he anisotropy of the confining potential, we were able to drive the system from 2D to 1D; this change occurs through a series of structural transition s. These transitions are reflected in the mode spectrum which collapses int o a narrower frequency region with increasing anisotropy.