Stochastic estimation of nuclear level density in the nuclear shell model: An application to parity-dependent level density in 58Ni

We introduce a novel method to obtain level densities in large-scale shell-model calculations. Our method is a stochastic estimation of eigenvalue count based on a shifted Krylov-subspace method, which enables us to obtain level densities of huge Hamiltonian matrices. This framework leads to a successful description of both low-lying spectroscopy and the experimentally observed equilibration of Jπ=2+Jπ=2+ and 2−2− states in 58Ni in a unified manner.