  Understanding the interplay between ordered structures and substrate
curvature is an interesting problem with versatile applications, including
functionalization of charged supramolecular surfaces and modern microfluidic
technologies. In this work, we investigate the two-dimensional packing
structures of charged particles confined on a pinched sphere. By continuously
pinching the sphere, we observe cleavage of elongated scars into pleats,
proliferation of disclinations, and subsequently, emergence of a depletion zone
at the negatively curved waist that is completely void of particles. We
systematically study the geometrics and energetics of the depletion zone, and
reveal its physical origin as a finite size effect, due to the interplay
between Coulomb repulsion and concave geometry of pinched sphere. These results
further our understanding of crystallography on curved surfaces, and have
implications in design and manipulation of charged, deformable interfaces in
various applications.
