Nonperturbative treatment of multielectron processes in ion-molecule scattering: Application to He2+-H2collisions

Abstract

We present a nonperturbative theory to describe multielectronic processes occurring in the course of collisions between an ion and a molecule. The approach is based on the expansion of the electronic scattering wave function onto asymptotic mono-or multicenter states with proper translational conditions and includes both static and dynamical electronic correlations. Therefore, it has a wide application range around intermediate impact velocitieswhere v e is the averaged electron velocity in the initial state. As a first application, we report results on single-and double-electron capture processes in He 2+ -H 2 collisions for impact energies ranging from 0.01 to 25 keV/u. Special emphasis on the prediction of cross sections for double-electron capture into doubly excited states of helium is addressed.

Radiative Cascade Repopulation of 1s2s2p 4P States Formed by Single Electron Capture in 2–18 MeV Collisions of C4+ (1s2s 3S) with He

“…These were computed in [30] for 2p SEC using ab initio dynamical calculations involving three active electrons within a full configuration interaction approach. This involved a semiclassical atomic orbital close-coupling calculation (referred to as 3eAOCC), with asymptotic descriptions of the atomic collision partners [65][66][67]: the time-dependent Schrödinger equation was solved non-perturbatively, with the inclusion of all couplings related to the static and dynamic interelectronic repulsions and effects stemming from the Pauli exclusion principle. This approach allows for the accurate modeling of the C 4+ and C 3+ electronic structures, including spin and spatial components.…”

Pauli Shielding and Breakdown of Spin Statistics in Multielectron Multi-Open-Shell Dynamical Atomic Systems

“…In parallel with the experimental investigations, we have performed ab initio dynamical calculations involving three active electrons within a full configuration interaction approach. Our treatment is based on a semiclassical atomic orbital close-coupling approach (referred to as 3eAOCC in the following), with asymptotic descriptions of the atomic collision partners [24,39,40]: the time-dependent Schrödinger equation is solved non perturbatively, with inclusion of all couplings related to the static and dynamic interelectronic repulsions and effects stemming from the Pauli exclusion principle. This allows for an accurate modelling of the C 4+ and C 3+ electronic structures, including spin and spatial components, and of their dynamics inducing, among others, excitation and capture to doubly excited states on the carbon center [41].…”

Theoretical Methods for Ultrafast Spectroscopy

“…Many methods are based on the SAE approximation, as mentioned in the introduction, often to simulate processes involved in high harmonic generation. [67] Related, highly specific methods have been used for instance to discuss He 2 + + H 2 collisions, [68] or the interaction of atoms and molecules with high intensity radiation, as reviewed in ref. [39,40], where the strong-field approximation (SFA) is made.…”