  Analysis of the collective structure of 0^{+} states in terms of phonon
tations for great amount of nuclei is presented .It is shown that the
rotational bands built on these states strongly depend on their structure. The
spectrum of the bands is obtained by the application of the Nuclear Surface
Oscillation /NSO/ model and assumption of "Kassini form" for the nuclear shape.
The yrast lines energies can be successfully described by the crossing of the
different rotational "beta - bands", if the collective structure of these band
heads is properly taken into account.

Nuclear Theory