  The ab initio symmetry-adapted no-core shell model naturally describes
nuclear deformation and collectivity, and is therefore well-suited to studying
the dynamics and coexistence of shapes in atomic nuclei. For the first time, we
analyze how these features in low-lying states of 6Li and 12C are impacted by
the underlying realistic nucleon-nucleon interaction. We find that the
interaction parametrization has a notable but limited effect on collective
shapes in the lowest 6Li and 12C states, while collective structures in the
excited 2+ state of 12C are significantly more sensitive to the interaction
parameters and exhibits emergent shape coexistence.
