Pathological behavior in the spectral statistics of the asymmetric rotor model

Phys Rev E Stat Nonlin Soft Matter Phys. 2001 Dec;64(6 Pt 2):066201. doi: 10.1103/PhysRevE.64.066201. Epub 2001 Nov 19.

Abstract

The aim of this work is to study the spectral statistics of the asymmetric rotor model (triaxial rigid rotator). The asymmetric top is classically integrable and, according to the Berry-Tabor theory, its spectral statistics should be Poissonian. Surprisingly, our numerical results show that the nearest-neighbor spacing distribution P(s) and the spectral rigidity Delta(3)(L) do not follow Poisson statistics. In particular, P(s) shows a sharp peak at s=1 while Delta(3)(L) for small values of L follows the Poissonian predictions and asymptotically it shows large fluctuations around its mean value. Finally, we analyze the information entropy, which shows a dissolution of quantum numbers by breaking the axial symmetry of the rigid rotator.