Abstract

The free electron on a helix with periodic boundary conditions is undoubtedly one of the simplest quantum
chemical models exhibiting both chirality and orbital angular momentum. Subjected to a light beam
traveling parallel to the helix axis, the model exhibits natural circular dichroism and, assuming a lifting of
the magnetic degeneracy by an external static magnetic field, also magnetic circular dichroism and
magnetochiral dichroism. We believe that the model illustrates well the interplay of chirality and
magnetism in a pure magnetic state, and that it could also be of interest in the study of the recently
discovered chiral ferromagnets.