Shape coexistence in doubly-magic 56 Ni by the Monte Carlo shell model

The structure of low-lying states of ${}^{56}\mathrm{Ni}$ is studied by the Monte Carlo shell model based on the quantum Monte Carlo diagonalization method. The coexistence of spherical yrast, prolate deformed, and other non-yrast states is described by the full $\mathrm{pf}$-shell calculations, by employing the FPD6 realistic residual interaction. To understand the properties of eigenstates thus obtained, we utilize a mean field analysis, such as a potential energy surface by constrained Hartree-Fock method.