Mean Field Dynamics and Low-Lying Collective Excitations

Collective Paths Connecting the Oblate and Prolate Shapes in 68Se and 72Kr Suggested by the Adiabatic Self-Consistent Collective Coordinate Method

“…Their energy differences are 0.30 and 0.82 MeV for 68 Se and 72 Kr, respectively. In the QRPA calculations at these local minima, we obtain strongly collective quadrupole modes with low frequencies.…”

“…For the P+Q Hamiltonian described in §4, the lowest HB solution corresponds to a oblate shape, while the second lowest HB solution possesses a prolate shape for both 68 Se and 72 Kr (see Table II). Their energy differences are 0.30 and 0.82 MeV for 68 Se and 72 Kr, respectively.…”

“…The major task here is to develop a practical procedure for solving the basic equations of the ASCC method in order to obtain a self-consistent collective path. We investigate, as typical examples, the oblate-prolate shape coexistence phenomena in 68 Se and 72 Kr, 41), 42) and we find that the self-consistent collective paths run approximately along the valley connecting the oblate and prolate local minima in the collective potential energy landscape. To the best of our knowledge, this is the first time that, starting from the microscopic P+Q Hamiltonian, the collective paths have been fully self-consistently obtained for realistic situations, although a similar approach to the study of large amplitude collective motion was recently employed by Almehed and Walet.…”

“…6)-33) Shape coexistence phenomena are typical examples of large amplitude collective motion in nuclei, and both experimental and theoretical investigations of such phenomena are currently being carried out. 34)- 57) We are particularly interested in the recent discovery of two coexisting rotational bands in 68 Se and 72 Kr, which are associated with oblate and prolate intrinsic shapes. 41), 42) Clearly, these data strongly call for further development of a theory that is able to describe them and revise our understanding of nuclear structure.…”

“…In §4, an algorithm to solve the basic equations of the ASCC method is discussed. In §5, we present the results of numerical calculations for the oblate-prolate shape coexistence phenomena in 68 Se and 72 Kr. Concluding remarks are given in §6.…”