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Nonaxial-octupole Y_{32} correlations in N = 150 isotones from multidimensional constrained covariant density functional theories

The non-axial reflection-asymmetric $β_{32}$ shape in some transfermium nuclei with N=150, namely $^{246}$Cm, $^{248}$Cf, $^{250}$Fm, and $^{252}$No are investigated with multidimensional constrained covariant density functional theories. By using the density-dependent point coupling covariant density functional theory with the parameter set DD-PC1 in the particle-hole channel, it is found that, for the ground states of $^{248}$Cf and $^{250}$Fm, the non-axial octupole deformation parameter $β_{32} > 0.03$ and the energy gain due to the $β_{32}$ distortion is larger than 300 keV. In $^{246}$Cm and $^{252}$No, shallow $β_{32}$ minima are found. The occurrence of the non-axial octupole $β_{32}$ correlations is mainly from a pair of neutron orbitals $[734]9/2$ ($νj_{15/2}$) and $[622]5/2$ ($νg_{9/2}$) which are close to the neutron Fermi surface and a pair of proton orbitals $[521]3/2$ ($πf_{7/2}$) and $[633]7/2$ ($πi_{13/2}$) which are close to the proton Fermi surface. The dependence of the non-axial octupole effects on the form of energy density functional and on the parameter set is also studied.