Highly correlated QDPT-CI calculations of valence and core photoelectron spectra of Ne Original Research Article

Quasidegenerate perturbation theory within the configuration interaction approach (QDPT-CI) is applied to the calculation of the valence and core photoelectron spectra of the Ne atom. A detailed investigation on the requirements of basis set and correlation level for convergent calculations is performed relative to the main ionizations, showing the importance of the inclusion of high angular momentum functions in the basis set; also the contribution of core valence correlation is pointed out. A basis set limited to f functions enlarged to Rydberg components is used to analyse the convergence of the results in a series of QDPT-CI calculations with a zero-order space R progressively enlarged, allowing to obtain absolute errors on the energies within 0.2 eV in the entire manifold of the ionic states. The well-defined scheme 2h-1p/4h-3p QDPT-CI appears adequate to describe quantitatively both the energies and intensities of the core and valence satellite structure of Ne and can represent a good compromise for applications to larger systems.