INFORMATION ENTROPY, CHAOS AND COMPLEXITY OF THE SHELL-MODEL EIGENVECTORS

The energies and wave functions of stationary many-body states are ana lyzed to look for the signatures of quantum chaos. Realistic shell mod el calculations are performed in the JT-scheme for 12 particles in the sd-shell. Local level statistics are in perfect agreement with the GO E predictions whereas the eigenvectors show evidence for non-complete energy dependent chaoticity. The information entropy of individual eig envectors turns out to be a convenient measure of degree of complexity of individual wave functions, We discuss the representation dependenc e and the sensitivity to the interaction strength. The exceptional rol e of the mean field basis is stressed.