Nonperiodic orbit sums in Weyl's expansion for billiards.
Weyl's expansion for the asymptotic mode density of billiards consists of the area, length, curvature, and corner terms. The area term has been associated with the so-called zero-length orbits. Here, closed nonperiodic paths corresponding to the length and corner terms are constructed.
Zheng
W M
WM
Institute of Theoretical Physics, Academia Sinica, Beijing 100080, China.