Electron-electron interaction effects in heliumlike atoms confined infinite external square-well potential

A B-spline-based configuration interaction method is used to compute the energy levels of the ground and a few excited states of heliumlike atoms confined in a finite external square-well potential, as a function of the depth of the con. ning shell potential. The electron probability density and the dependence of the energy levels in the shell potential are used to account for the electron-electron interaction when the atoms are submitted to such an environment.