Linear chain structure of four-$\alpha$ clusters in $^{16}$O
  We investigate the linear-chain configurations of four-$\alpha$ clusters in $^{16}$O using a Skyrme cranked Hartree-Fock method and discuss the relationship between the stability of such states and angular momentum. We show the existence of a region of angular momentum (13-18 $\hbar$) where the linear chain configuration is stabilized. For the first time we demonstrate that stable exotic states with a large moment of inertia ($\hbar^2/2\Theta$ $\sim$ 0.06-0.08 MeV) can exist. 
T. Ichikawa, J. A. Maruhn, N. Itagaki, and S. Ohkubo
nucl-th