Eigenvalues in gaps of perturbed periodic Dirac operators: Numerical evidence (Q1860440)

The spectrum of a periodic Dirac system shows characteristic gaps. A perturbation of the system leads to the emergence of eigenvalues in these gaps. The author presents a numerical method for studying the distribution of the eigenvalues introduced by a perturbation of angular momentum type. The method is based on reducing the problem to the determination of the half-plane number of certain Prüfer angles and is applied to a number of concrete examples.