Harris-Nesbet method for electron-Li²⁺ collisions: determination of the singlet S-wave doubly excited states of Li⁺ below the N=2 threshold of Li²⁺

Abstract

The positions and widths of the singlet S-wave doubly excited state resonances ¹Se of Li⁺ at energy below the N=2 threshold of Li²⁺ are determined, employing a numerical procedure developed earlier for electron collisions with hydrogenlike ions within the Harris-Nesbet variational method. Altogether, twenty of these singlet S-wave doubly excited states are located below this threshold with their widths determined. Some of these doubly excited states are determined for the first time by the present calculation. Our results are compared, with discussion, to those obtained by various other research groups using different numerical methods of approach for their calculations. Graphical presentation of all these twenty doubly excited states is given.