Photo-Ionization of Molecules near Threshold

Abstract
An orthogonalized Coulomb-wave method for the construction of continuum wave functions of molecules is described. Hydrogenic functions of definite angular momentum, which transform according to the irreducible representations of the point group of the molecule, are phenomenologically used as trial functions. Corrections to the trial functions are made by orthogonalizing them to charge rearrangement states of the molecule. The photo-ionization cross section is obtained by summing over the asymptotic angular-momentum quantum number. The method is exemplified by calculation of the photo-ionization cross sections of the ground and first excited states of the anthracene molecule in the range of 1.5 eV above threshold.