@article{oai:nitech.repo.nii.ac.jp:00005389,
 author = {Arita, Ken-ichiro and Brack, Matthias},
 issue = {5},
 journal = {PHYSICAL REVIEW E},
 month = {May},
 note = {We apply periodic orbit theory to a two-dimensional nonintegrable billiard system whose boundary is varied smoothly from a circular to an equilateral triangular shape. Although the classical dynamics becomes chaotic with increasing triangular deformation, it exhibits an astonishingly pronounced shell effect on its way through the shape transition. A semiclassical analysis reveals that this shell effect emerges from a codimension-2 bifurcation of the triangular periodic orbit. Gutzwiller’s semiclassical trace formula, using a global uniform approximation for the bifurcation of the triangular orbit and including the contributions of the other isolated orbits, describes very well the coarse-grained quantum-mechanical level density of this system.We also discuss the role of discrete symmetry for the large shell effect obtained here., application/pdf},
 pages = {056211-1--056211-13},
 title = {Anomalous shell effect in the transition from a circular to a triangular billiard},
 volume = {77},
 year = {2008}
}