Two-dimensional molecular-dynamics simulations of finite, strongly coupled dusty-plasma clusters reveal how their equilibrium structure depends on size. As the number of charged grains changes, the cluster crosses over from bulk-dominated (macroscale) to surface-dominated (microscale) behaviour, and under transverse confinement the grains settle into concentric multi-ringed shells whose ring count and size grow with particle number. The distinctive result is that the birth of each new ring is always heralded by a configuration with fivefold (pentagonal) symmetry in the core, a signature that persists across different boundary-condition symmetries and different Yukawa shielding lengths.
Using two-dimensional molecular-dynamics simulations, this paper studies size-dependent structure in finite, strongly coupled dust clusters and the crossover from bulk-dominated (macroscale) to surfa…