TWO-PHOTON DETACHMENT FROM HALOGEN NEGATIVE IONS 
G.F.Gribakin, V.K.Ivanov, A.V.Korol and M.Yu.Kuchiev
University of New South Wales, Sydney, Australia; St.Petersburg State
Technical University, ST.Petersburg, Russia; Russian Maritime Technical
University, St.Petersburg, Russia
Two-photon detachment cross sections and photoelectron angular 
distributions for halogen negative ions are calculated within the lowest
order of perturbation theory. The calculations are performed both within
the Hartree-Fock approximation and within the method combining the
corrected ground state and the Hartree-Fock excited state wavefunctions.
We show that imposing a correct asymptotic behaviour of the ground state
wavefunction has a significant effect on the cross section values.