We present a microscopic description of nuclei in an intermediate-mass
region, including the proximity to the proton drip line, based on a no-core
shell model with a schematic many-nucleon long-range interaction with no
parameter adjustments. The outcome confirms the essential role played by the
symplectic symmetry to inform the interaction and the winnowing of shell-model
spaces. We show that it is imperative that model spaces be expanded well beyond
the current limits up through fifteen major shells to accommodate particle
excitations that appear critical to highly-deformed spatial structures and the
convergence of associated observables.Comment: 9 pages, 8 figure
