Electrons and photons colliding with atoms: development and application of the convergent close-coupling method

Abstract

The substantial progress that has occurred during the 1990s in the field of electron-atom-collision theory is discussed. We show how a solution of a small-model three-body problem, using the convergent close-coupling method, has led to numerous applications involving real atomic collision systems. Consequently many fundamental electron-atom collision processes are considered as `solved', and accurate collision data of interest to science and industry have become available. However, we suggest that the present has only just seen the birth of modern atomic collision theory. There are many more important collision problems to be tackled, with guidance coming from experiment being as important as ever.

Non-LTE Model Atom Construction

“…Recently, breakthrough results have been obtained by use of the converging close-coupling method. Several fundamental processes have been modelled accurately, providing cross sections that closely reproduce the available experimental data in these cases, see Bray et al (2002) for a review.…”

Calculation of (e, 2e) triple differential cross sections of Mg in coplanar geometry

“…The electron-electron potential 3 v is responsible for ionization and U is the distorting potential. Equation (1) (4) and (5) are direct and exchange amplitudes for ionization from the (n, l ) shell of the target atom where nl ψ is the corresponding target orbital from which ionization is taking place and n and l are the principal and orbital quantum number respectively.…”

“…(e, 2e) processes) of atoms and ions provides important information about target structure, target wavefunction and collision dynamics. Since the experiment of Ehrhardt et al [1] extensive studies have been performed for the electron impact single ionization of hydrogen [2] and helium [3] atoms in different geometrical arrangements. Apart from hydrogen and helium atoms, (e, 2e) studies have been performed on a number of targets using different theoretical approaches (see review articles [4][5][6][7][8]).…”

Molecular ionization and dissociation using synchrotron radiation and ultrashort laser pulses

“…Notice that, in order to perform the integral over R in equation (1), this wave function must be obtained at different values of R. Several accurate methods have been successfully developed to evaluate ψ 0+ αlαǫα (r, R). Among them, it is worth mentioning (i) the discretized close-coupling (DCC) method [12,[17][18][19] and the convergent close-coupling (CCC) method [20][21][22], in which the electronic wave function is written as a combination of products of target and scattering electronic wave functions with the appropriate boundary conditions, (ii) the exterior complex scaling (ECS) method [23][24][25], in which the electronic coordinates are scaled in the complex plane beyond a certain (usually large) distance r 0 thus ensuring the correct asymptotic behavior for r i < r 0 , and (iii) the Rmatrix method (and its many extensions, see, e.g., [26][27][28] and references therein), in which the problem is first solved within a sphere of finite size and then the asymptotic behavior is switched on later from outside the sphere. In principle, all these methods can be implemented by using different basis sets and/or grid methods.…”