Sum-over-states for PNC amplitude

An alternative and very direct way of calculating PNC transition amplitudes is to saturate the sum over exact many-body states X in 

One finds that about 98% of this sum is contributed by the states X = I6P1/2) I9F1/2), and the remaining 2% by the states with n 10, and by states in which X involves excitation of the core. If the exact wavefunctions 

X are replaced by the corresponding lowest-order Slater determinants, this expression can be shown to reproduce the result (85). Here, however, we evaluate the contributions from the states with valence principle quantum numbers n = 6 9 using our all-order wave functions the remaining contributions are estimated using perturbation theory. We find [40]  

This result is consistent with the mixed-parity determination. Our final result is an average of the two methods. We now turn to a discussion of smaller PNC effects. 

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