Post-prior discrepancyand dynamic electron screening

MONTI, JUAN MANUEL; FOJÓN, OMAR ARIEL; HANSSEN, JOCELYN; RIVAROLA, ROBERTO DANIEL

Salamanca, España

Conferencia; ECAMP 2010 - 10th International Conference on Atoms, Molecules and Photons; 2010

<!-- @page { margin: 2cm } P { margin-bottom: 0.21cm } -->The continuum distorted wave [1] and the continuum distorted wave-eikonal initial state (CDW-EIS) [2] models, which were formulated to describe electron ionization in ion-atom collisions, contain approximately all orders of the Born series. Thus, they were introduced in order to accelerate its convergence and to avoid divergences due to disconnected diagrams characteristic of the Born sub-series. They were proposed to study monoelectronic targets. Later, an extension was made by Fainstein et al. [3] for multielectronic targets, reducing the multielectronic case to a monoelectronic one. In this formalism, the operation of the perturbative potentials on the initial and final distorted wavefunctions gives place to the so-called prior- and post-versions of the transition matrix, respectively. To facilitate their calculation, and the corresponding cross sections, effective coulomb potentials were chosen to represent the interaction between the residual target and the active electron in the exit channel. Thus prior- and post-versions of the transition matrix elements gave place to different cross section values. This was observed as a resulting post-prior discrepancy between these two versions. Recently, we revisited the formulation of the post-version of the CDW-EIS approximation [4] showing that a residual potential that was neglected in previous works must be included to obtain agreement with prior-version calculations. This potential is associated with a correct description of the dynamic screening produced by the passive electrons on the evolution of the active one and its inclusion allows the evaluation of the influence of this interaction on single ionization cross sections. In [4], the initial bound wavefunction was described by a single-zeta Rothaan-Hartree-Fock (RHF) representation. With this choice for the initial bound wavefunction, the post-prior discrepancy was widely diminished. In the present work, we use a more complete five-zeta RHF representation of the initial bound wavefunction, showing that with this choice the post-prior discrepancy is completely vanished. Results for double differential cross sections will be presented during the conference. References: [1] Belkić Dž 1978 J. Phys. B: At. Mol. Phys. 11 3529 [2] Crothers D S F and McCann J F 1983 J. Phys. B: At. Mol. Phys. 16 3229 [3] Fainstein P D, Ponce V H and Rivarola R D 1988 J. Phys. B: At. Mol. Opt. Phys. 21 287 [4] Monti J M, Fojón O A, Hanssen J and Rivarola R D 2010 J. At. Mol. Opt. Phys. (in press)