Searching for a4αlinear-chain structure in excited states ofO16with covariant density functional theory

Abstract

A study of the $4\ensuremath{\alpha}$ linear-chain structure in high-lying collective excitation states of $^{16}\mathrm{O}$ 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 $4\ensuremath{\alpha}$ clusters stay along a common axis. The strongly deformed rod shape also appears in the high-spin region with the angular momentum $13\ensuremath{\hbar}\phantom{\rule{4.pt}{0ex}}\text{to}\phantom{\rule{4.pt}{0ex}}18\ensuremath{\hbar}$; however, whether the state is a pure $4\ensuremath{\alpha}$ linear chain is less obvious than for the low-spin states.