Nuclear Shell Model by the Quantum Monte Carlo Diagonalization Method

The feasibility of shell-model calculations is radically extended by the quantum Monte Carlo diagonalization method with various essential improvements. The major improvements are made in the sampling for the generation of shell-model basis vectors, and in the restoration of symmetries such as angular momentum and isospin. Consequently the level structure of low-lying states can be studied with realistic interactions. After testing this method on ${}^{24}\mathrm{Mg}$, we present first results for energy levels and $E2\mathrm{}$ properties of ${}^{64}\mathrm{Ge}$, indicating its large and $\gamma$-soft deformation.