  The ground state band was recently observed in the superheavy nucleus 256Rf.
We study the rotational properties of 256Rf and its neighboring even-even
nuclei by using a cranked shell model (CSM) with the pairing correlations
treated by a particle-number conserving (PNC) method in which the blocking
effects are taken into account exactly. The kinematic and dynamic moments of
inertia of the ground state bands in these nuclei are well reproduced by the
theory. The spin of the lowest observed state in 256Rf is determined by
comparing the experimental kinematic moments of inertia with the PNC-CSM
calculations and agrees with previous spin assignment. The effects of the high
order deformation varepsilon6 on the angular momentum alignments and dynamic
moments of inertia in these nuclei are discussed.
