Doubly excited states of two-electron atoms

Precise energy eigenvalues of doubly excited 1 , 3 D o states originating from 2pnd ( n = 3 – 8 ) configuration of two-electron atoms ( Z = 3 – 7 ) have been calculated by using Ritz variational method in Hylleraas coordinates. Except for a few, the present non-relativistic energy values are the lowest yet obtained. The energy eigenvalues of a number of these states are being reported for the first time. Comparisons with existing experimental results are also made. The effective quantum numbers ( n ∗ ) for the states mentioned above have been calculated using the theory of quantum defect.