U. Peskin et N. Moiseyev, TIME-INDEPENDENT SCATTERING-THEORY FOR TIME-PERIODIC HAMILTONIANS - FORMULATION AND COMPLEX-SCALIGN CALCULATIONS OF ABOVE-THRESHOLD-IONIZATION SPECTRA, Physical review. A, 49(5), 1994, pp. 3712-3728
A time-independent scattering theory is introduced for time-periodic H
amiltonians. The theory is applicable in cases where at infinite time
(t = +/- infinity) the relative motion between the colliders is free,
and therefore the asymptotic kinetic energy can be defined experimenta
lly. This asymptotic condition and the time periodicity of the Hamilto
nian lead to time-independent expressions for the distribution of the
kinetic energy in the relative motion of the fragments for a half-coll
ision and for a full-collision experiment. These expressions are combi
ned with the complex-coordinate method to give an efficient numerical
algorithm for the calculation of multiphoton ionization-dissociation p
robabilities within the framework of the finite-range-potential approx
imations. The theory is applied to a model Hamiltonian of an atom in a
strong ac field. The obtained above-threshold-ionization spectra are
in excellent agreement with theoretical results previously obtained fr
om time-dependent calculations.