GENERAL PROPERTIES OF HARMONIC GENERATION SUSCEPTIBILITIES

摘要

We derive the asymptotic behaviour of the n~(th) order harmonic generation susceptibility using the Kubo response function formalism: it is characterized by a ω~(-2n-2) dependence and a coefficient proportional to the trace of the (n+1)~(th) derivative of the potential energy on the equilibrium density matrix. Using this result and the analytical properties of the susceptibility considered we derive new Kramers-Kroenig relations and sum rules. The general properties obtained show a strict correspondence with those already obtained with the classical anharmonic oscillator model.