Nuclear structure study around Z=28

Yrast levels of Ni, Cu and Zn isotopes for $40\le N\le 50$ have been described by state-of-the-art shell model calculations with three recently available interactions using ${}^{56}$Ni as a core in the $f_{5\mathrm{/}2}p{g}_{9\mathrm{/}2}$ model space. The results are unsatisfactory viz. large $E(2^{+})$ for very neutron rich nuclei, small B(E2) values in comparison to experimental values. These results indicate an importance of inclusion of $\pi f_{7\mathrm{/}2}$ and $\nu d_{5\mathrm{/}2}$ orbitals in the model space to reproduce collectivity in this region.