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.

According to the principle of a new scanning electron microscope and the mechanism of the interaction between electron beam and solid target,the trajectories of an incident electron in a sample are simulated,a simulation program is compiled using the Monte Carlo method,and the backscattering coefficients corresponding to different parameters of the SEM are obtained.