A Relativistic Complex Optical Potential Calculation for Electron-Beryllium Scattering: Recommended Cross Sections

We report results from the application of the relativistic complex optical potential (ROP) method to electron-beryllium scattering. The energy range of this study was 0-5000 eV, with the results for the integral elastic cross sections, momentum transfer cross sections, summed discrete electronic-state excitation integral cross sections, and total ionisation cross sections (TICSs) being reported. However we will largely focus our discussion here on the TICS, due to its importance in simulating the plasma action on beryllium (Be) in the international thermonuclear reactor. The current level of agreement between the various theoretical approaches to calculating the TICS is well summarised in the work of Maihom et al. [Eur. Phys. J. D 67, 2 (2013)] and Blanco et al. [Plasma Sources Sci. Technol. 26, 085004 (2017)], with the level of accord between them being quite marginal. As a consequence, we revisit this problem with improved scattering potentials over those employed in the work of Blanco et al. In addition, we present results from an application of the binary-encounter-Bethe theory for the electron-Be TICS. We find a quite significant improvement in the level of agreement between the TICS from our new ROP calculation and the earlier B-spline R-matrix and convergent close coupling results [O. Zatsarinny et al., J. Phys. B: At., Mol. Opt. Phys. 49, 235701 (2016)], compared to that reported in the work of Blanco et al. As a result of this improved level of accord, we propose here a recommended TICS for e+Be scattering, as well as for the elastic integral and summed electronic-state excitation cross sections, which also incorporates uncertainty estimates for their validity.