Electronic excitation of the b state of by electron impact using the method of continued fractions

Abstract

The method of continued fractions (MCF) of Horáček and Sasakawa is applied for the first time to the study of low-energy electron scattering by linear molecules at the twostate close-coupling level. In particular, we have calculated the excitation cross sections for the transition X 1 + g → b 3 + u in H 2 for incident energies from near threshold to 40 eV. In contrast to the early two-state studies of Chung and Lin, in this work no orthogonality constraint between the bound and continuum orbitals is imposed and the one-electron exchange terms are considered explicitly. The calculated cross sections are in very good agreement with the available experimental data and with some recent theoretical results.

Cross sections for electron-impact excitation of the H2molecule using the MOB-SCI strategy

“…Particularly, we note that at the energies of 12 and 20 eV our DCS reproduce the small angle behaviour observed in the measurements from Nishimura and Danjo [11] and Khakoo and Segura [16]. These results clearly denote an improvement on previous two-channel calculations from Lima et al [22] (SMC) and Lee et al [26] (MCF), and also on the strong close-coupling calculations from Branchett et al [32] (R-matrix) and Machado et al [28] (MCF). Although not shown, at 13 eV there is a similar agreement between the MOB-SCI differential cross section and measured values from [11].…”

“…For the incident energy of 30 eV, our DCS is better compared to the experimental data from Khakoo and Trajmar [13] and lies systematically below the theoretical results from Lima et al [22] (SMC). The DCS also lies below the results obtained by Lee et al [26] and Machado et al [28] (MCF), except for angles above 150 • , where our result is a little bit more backward peaked. Figure 1(d) shows the integral cross section (ICS) for the X 1 (+) g → b 3 (+) u electronic transition.…”

Vibrational cross sections for positron scattering by nitrogen molecules

“…The BFVCC integral equations are solved using the multichannel version of method of continued fractions (MCF-MC) [11,12,29]. The application of MCF consists in defining a weakened interaction potential, in nth order as…”

“…The comparison of our results with the existing experimental and other calculated data is encouraging. Moreover, MCF was also successfully applied in cross-section calculations for electronimpact vibrational excitation of H 2 [11,12].…”

Multi‐channel coupling effects for electronic excitations leading to the b3∑, a3∑, and c3∏u states of H2

“…During the past two decades some multi‐channel methods of ab initio nature have been proposed for studies of electronic excitation of molecules by electron impact. These studies include the R‐matrix method 7, 8, the complex Kohn variation method 9, the Schwinger multichannel method (SMC) 10, and, lately, the method of continued fractions (MCF) 11–13. These methods have been applied for studies of electronic excitation of several molecular systems 14–18.…”