Journal of Physics B: Atomic, Molecular and Optical Physics
The study of 1/n expansions for various atomic matrix elements, where n is the principal quantum number, plays an important role in the theoretical foundations of the quantum defect method. The paper develops an expansion in powers of 1/n 2 for hydrogenic boundstate wavefunctions which can be used to calculate 1/n expansions of matrix elements. The 1/n expansions of the two-electron direct and exchange Coulomb integrals are evaluated as an example. © 1993 IOP Publishing Ltd.
Drake, Gordon W. F. and Hills, R. N.. (1993). 1/n expansions for two-electron Coulomb matrix elements. Journal of Physics B: Atomic, Molecular and Optical Physics, 26 (19), 3159-3176.