Chaos in the Classical Analogue of the Hofstadter Problem
  The behaviour of an electron in a potential that resembles that of a bidimensional solid with a perpendicular magnetic field applied is studied from a classical point of view. This problem presents the standard features of chaos and some interesting new patterns. A new chaos indicator, called random walk indicator, is presented to describe som of these new patterns 
M. del Mar Espinosa, Miguel A. Martin-Delgado, Alfonso Niella, David   Paramo and Javier Rodriguez-Laguna