Benchmark calculation of total cross sections for ionization–excitation of helium

Abstract

The total cross section for simultaneous ionization-excitation of helium by electron impact has been revisited within the framework of the fully nonperturbative B-spline R-matrix with pseudostates approach. A long-standing discrepancy regarding the absolute normalization of the cross section for ionization with simultaneous excitation of the residual ion into the He + (2p) is resolved in favour of the values suggested by Bloemen et al (1981

NonperturbativeB-splineR-matrix-with-pseudostates calculations for electron-impact ionization-excitation of helium to then=3states ofHeZatsarinny1, Bartschat2 2016Phys. Rev. ASelf Cite6110View full textAdd to dashboardCite

“…The set of pseudostates contained the configurations 1sn , 2 n , and 3 n , with the latter two sets describing doubly excited autoionizing states as well as the ionization-excitation process. Note that the increase of the principal quantum of the "core" electron from n = 2 [2,3] to n = 3 in the present work rapidly increased the number of states in the calculation, thereby limiting the highest pseudostate energy that we could handle.…”

“…In recent years, we have further developed a fully nonperturbative B-spline R-matrix (close-coupling) with pseudostates (BSRMPS) method and applied it to both direct ionization [1] and ionization with excitation problems [2,3]. Despite the success achieved in employing a projection approach to obtain the cross sections from excitation amplitudes of the positive-energy discrete (i.e., finite-range) pseudostates, some skepticism remains about the validity of the approach.…”

Multicenter distorted-wave method for fast-electron-impact single ionization of molecules

“…Different kinds of theoretical methods have been developed for the atomic system, such as the distorted-wave impulse approximation (DWIA) [1,9,10], distorted-wave Born approximation (DWBA) [9][10][11], Brauner-Briggs-Klar theory [12][13][14], Bspline R-matrix approach [15,16], convergent close-coupling (CCC) method [17][18][19], exterior complex scaling (ECS) * songbin@pks.mpg.de † xjun@ustc.edu.cn method [20][21][22], and time-dependent close-coupling (TDCC) method [23][24][25]. We note that the ECS, CCC, and TDCC methods could almost exactly solve the three-body system (electron plus hydrogen).…”

Role of ionization-excitation processes in the cross section for direct ionization of heavy atomic ions by electron impact

“…Ionization with simultaneous excitation is significantly more correlated, and hence its contribution to the ionization cross section is usually small compared with that of direct ionization processes [31,32]. Our results show, however, that the ionization cross section can be underestimated by about 15% if one neglect the contributions of ionization-excitation processes for heavy ions.…”