Molecular-orbital structure in neutron-rich C isotopes

The molecule-like structure of the C isotopes (A=12, 14, 16) is investigated using a microscopic α+α+α+n+n+· · · model. The valence neutrons are classified based on the molecular-orbit (MO) model, and both π-orbit and σ-orbit are introduced around three α-clusters. The valence neutrons which occupy the π-orbit increase the binding energy and stabilize the linear-chain of 3α against the breathing-like break-up. However, 14C with the π-orbit does not show clear energy minimum against the bending-like path. The combination of the valence neutrons in the πand the σ-orbit is promising to stabilize the linear-chain state against the breathingand bendingmodes, and it is found that the excited states of 16C with the (3/2π ) (1/2σ ) 2 configuration for the four valence neutrons is one of the most promising candidates for such