Semiclassical Calculation of Shell Effects in Deformed Nuclei
  We summarize recent work in which the shell effect, which causes the onset of the mass asymmetry in nuclear fission, could be explained semiclassically in the framework of the periodic orbit theory. We also present new results for the inclusion of a spin-orbit interaction in the semiclassical calculation of the level density. 
M. Brack, Ch. Amann