CALCULATION OF DOUBLY-EXCITED STATES OF HELIUM WITH A FINITE DISCRETESPECTRUM

Doubly excited states in helium are calculated with many-body perturba tion theory to all orders in the electron-electron interaction. A fini te and numerical basis set, rotated out into the complex plane, is use d. Results, for energies and widths, are presented for states with ele ctrons in the n = 2 and n = 3 states. The possibility of an accuracy o f a few parts in 10(6) is demonstrated. The method is equally applicab le to the study of doubly excited states of many-electron systems and the extension to the corresponding relativistic procedure is straightf orward.