  We study the properties of the nuclear rotational excitations with
hypothetical tetrahedral symmetry by employing the microscopic mean-field and
residual-interaction Hamiltonians with angular-momentum and parity projection
method; we focus on the deformed nuclei with tetrahedral doubly-closed shell
configurations. We find that for pure tetrahedral deformation the obtained
excitation patterns satisfy the characteristic features predicted by
group-representation theory applied to the tetrahedral symmetry group. We find
that a gradual transition from the approximately linear to the characteristic
rigid-rotor, parabolic energy-vs.-spin dependence occurs as a function of the
tetrahedral deformation parameter. The form of this transition is compared with
the similar well-known transition in the case of quadrupole deformation.
