Time-Dependent Close-Coupling Calculations of Dielectronic Capture in He

Abstract

We report on the first time-dependent close-coupling calculation of dielectronic capture into a doubly excited state of a two-electron atom. An incoming electron is represented by a Gaussian wave packet which collides with singly ionized helium in its ground state. The close-coupling equations describe the propagation of the total compound wave function on a two-dimensional radial lattice. By projecting this wave function onto a doubly excited state of neutral helium, we can determine the probability amplitude for dielectronic capture into one of these states and the subsequent autoionization from it.

The time-dependent close-coupling method for atomic and molecular collision processes

“…The TDCC method was extended to calculate energy and angle differential cross sections for the single ionization of helium in its ground state [45]. We note that the TDCC method has also been used to study doubly excited states of helium and their subsequent autoionization [46].…”

Simple correlated wavefunctions for the K-shell electrons of neutral atoms

“…In [26], a complete description of the theoretical procedure used here was presented for helium within a spherical symmetric model (also known as the Temkin-Poet model or the S-wave model [27,28]). The same method was also used before for real helium in a full CC calculation by Mitnik et al [29], and the detailed description of the theory for this case will appear in a forthcoming paper. The main difference with these previous calculations resides in the fact that as we are dealing now with general atoms and ions, the influence of the outer-shell electrons is taken into account here through the inclusion of the Hartree potential (equation (2)) in the close-coupling equations.…”

Helium atom in a box: a fully quantal solution

“…The net result from this imaginary time propagation is the enhancement of those components of the solution with smaller eigenvalues of H relative to those with larger eigenvalues. Doubly-excited autoionizing states are calculated by imposing additional constraints at the iteration of the relaxation, projecting out also the one-electron 1s component of the wave functions [1,3].…”