Heavy Deformed Nuclei in the Shell Model Monte Carlo Method

We extend the shell model Monte Carlo approach to heavy deformed nuclei using a new proton-neutron formalism. The low excitation energies of such nuclei necessitate low-temperature calculations, for which a stabilization method is implemented in the canonical ensemble. We apply the method to study a well-deformed rare-earth nucleus, ¹⁶²Dy. The single-particle model space includes the 50–82 shell plus 1f_7/2 orbital for protons and the 82–126 shell plus 0h_11/2, 1g_9/2 orbitals for neutrons. We show that the spherical shell model reproduces well the rotational character of ¹⁶²Dy within this model space. We also calculate the level density of ¹⁶²Dy and find it to be in excellent agreement with the experimental level density, which we extract from several experiments.