Physical Review C
Chaotic behavior in the cranking and particles-rotor models
András T. Kruppa, Károly F. Pál, N. Rowley
Abstract
We investigate the consequences on the order/chaos transition of replacing the scalar rotational energy of the particles-rotor model by a one-body cranking term. The nearest-neighbor distribution of energy levels and the spectral rigidity are studied as a function of the spin or cranking frequency, respectively. Exact energies for our statistical analyses are obtained from a full diagonalization of a many-body Hamiltonian with two-body forces for six particles in an ${\mathit{i}}_{13/2}$ shell coupled to a deformed core. In this model, the competing physical effects (two-body interaction strength, quadrupole deformation, and moment of inertia) are easily parametrized and studied. The dependence of the chaoticity on model parameters reveals the stabilizing influence of a large quadrupole deformation. For low spins, the considerable effects of the (effectively two-body) recoil term give significant differences between the two descriptions.