Physical Review A
An extension of work by Drake [Phys. Rev. A 18, 820 (1978)] to the treatment of radial and angular integrals occurring in N-electron systems is presented. It is shown that the essential results pertaining to two-electron systems adapted to Hylleraas coordinates also apply to many electrons when pairs of electrons are chosen to interact with each other in a spin-adapted basis set. These results are derived using graphical-analysis techniques in the context of the unitary-group approach. © 1992 The American Physical Society.
Kent, R. D. and Drake, Gordon W. F.. (1992). Many-electron radial and angular integrals in the unitary-group approach. Physical Review A, 45 (5), 3339-3342.