Searching for a 4α linear-chain structure in excited states of 16O with covariant density functional theory

A study of the 4 alpha linear-chain structure in high-lying collective excitation states of O-16 with covariant density functional theory is presented. The low-spin states are obtained by configuration mixing of particle-number and angular-momentum projected quadrupole deformed mean-field states with the generator coordinate method. The high-spin states are determined by cranking calculations. These two calculations are based on the same energy density functional PC-PK1. We have found a rotational band at low spin with the dominant intrinsic configuration considered to be the one whereby 4 alpha clusters stay along a common axis. The strongly deformed rod shape also appears in the high-spin region with the angular momentum 13 (h) over bar to 18 (h) over bar; however, whether the state is a pure 4 alpha linear chain is less obvious than for the low-spin states.