The B -spline R -matrix method applied to photoionisation of neon

Abstract We present calculations for the total photoionisation cross section of neon from its ground state using the B -spline R -matrix ( BSR ) method within the LS -coupling framework. An extensive 38-state target model, previously described by Feist et al (2014 Phys. Rev. A 89 033417), is used to carry out the full calculation, while subsets of this model are used to study the convergence of the predicted photoionisation cross section, in particular the resonance structure, with respect to both the completeness of the Ne + basis set and the form (length or velocity) of the dipole operator. The calculated total photoionisation cross section is in excellent agreement with the experimental data of Samson and Stolte (2002 J. Elect. Spect. Relat. Phenom. 123 265) over the broad photon energy range above the first ionisation threshold, from 21.6 eV to 125 eV. We also present results for selected features in the series of resonances that are encountered in the energy range of 1.60 Ry to 2.53 Ry above the Ne + ground state. In particular, we present calculations for the 2.32 Ry–2.49 Ry energy range, which contains several overlapping Rydberg series. Throughout, we demonstrate the essential role that additional target states play in the predicted photoionisation cross section, especially within the resonance region.