HARMONIC-GENERATION IN IONIZING SYSTEMS BY THE COMPLEX SCALED ADIABATIC-SWITCH METHOD

An adiabatic-switch method for calculating harmonic generation under i ntense laser radiation is presented. The adiabatic switch is first app lied to nonbound (i.e., ionizing or dissociative) time-periodic Hamilt onians when the energy spectrum is degenerate. Our derivation is based on the use of Floquet theory combined with complex scaling and of a g eneralized definition of the inner product for non-Hermitian operators . A model potential representing a Xe atom in the presence of a laser field is studied as an example to illustrate the numerical advantages of the present method and its stability.