A numerical ab initio study of harmonic generation from a ring-shaped model molecule in laser fields

When a laser pulse impinges on a molecule which is invariant under certain symmetry operations selection rules for harmonic generation (HG) arise. In other words, symmetry controls which channels are open for the deposition a nd emission of laser energy-with the possible application of filtering or a mplification. We review the derivation of HG selection rules and study nume rically the interaction of laser pulses with an effectively one-dimensional ring-shaped model molecule. The harmonic yields obtained from that model a nd their dependence on laser frequency and intensity are discussed. In a re al experiment obvious candidates for such molecules are benzene, other arom atic compounds, or even nanotubes.