Os-Pt区核的基态三轴形状

在偶-偶核基态中寻找稳定的三轴形状， 其中最大三轴形变为$ \left| \gamma \right| $≈30°，仍然是核结构的一个主要主题。 在本工作中，使用推转Woods-Saxon(WS)壳模型来研究Os-Pt区基态和集体转动态中可能的三轴形状。为寻找核态可能存在的三轴形变，具体用对力-形变-转动频率自洽推转壳模型对偶-偶176-202Os和182-204Pt同位素进行了总Routhian面计算。计算是在四极形变(${\beta _2} $, $ \gamma $)网格中进行的，而十六极形变${\beta _4} $可变。事实上，在四极形变(${\beta _2} $, $\gamma $)的每个网格点上，计算的能量相对于十六极形变$ {\beta _4} $最小化。发现某些核的基态譬如196Os和188-194Pt既非扁椭球亦非长椭球， 而是在这些核中基态极小值是形状非轴对称的，即三轴形变。同时, 我们把从实验数据提取出的转动惯量与我们的计算结果作比较, 显示实验数据不能很好地与转动假定相一致，说明有振动行为。此外，我们使用一种辅助的方法提取了平衡$\gamma _{0} $值，该值支持我们的预言。

Triaxial Shape of Ground State in Os-Pt Region

The search for stable triaxial shapes in the ground states of even-even nuclei, with a maximum triaxial deformation of $ \left| \gamma \right| $≈30°, is still a major theme in nuclear structure. In the present work, we use the cranked Woods-Saxon(WS) shell model to investigate possible triaxial shapes in ground and collective rotational states of Os-Pt region. Specifically, total-Routhian-surface calculations by means of the pairing-deformation-frequency self-consistent cranked shell model have been carried out for even-even 176-202Os and 182-204Pt isotopes, in order to search for possible triaxial deformations of nuclear states. Calculations are performed in the lattice of quadrupole ($\, {\beta _2} $, $ \gamma $) deformations with the hexadecapole $\, {\beta _4} $ variation. In fact, at each grid point of the quadrupole deformation ($\, {\beta _2} $, $\gamma $) lattice, the calculated energy has been minimized with respect to the hexadecapole deformation $\, {\beta _4} $. It is found that some nuclear ground states such as in 196Os and 188-194Pt are neither oblate nor prolate. Instead, the ground states minima in these nuclei are axially asymmetric in shape, i.e., triaxial deformation. At the same time, we compare the experimentally deduced moments of inertia with our calculated results, which show that the experimental data do not agree well with the assumption of rotational motion. This indicates that they have vibrational behavior. In addition, a complementary approach is used to extract equilibrium ${ \gamma _0} $ value, which support our predictions.