Abstract: A nonlinear optimizing method is applied to study the ground state configurations of a two-dimensional charged particle system in a hard-wall confining potential.We find that the circular shell configurations in a circular hard wall confinement are similar to that in a parabolic confining potential.With a hard-wall square boundary,the Wigner crystal lattice is square as the number of particles N<66,but becomes a hexagon as N≥66 since the boundary effect is weak for inner particles.The influence of the elliptic and rectangular boundary on the wigner crystal lattice is analyzed.

Key words: wigner crystal lattice, boundary effect