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> The "non-anomalous" contribution is the atomic scattering factor, f. f' > and f" are interdependent, (like ORD and CD are one amnifestation of the > same > physical phenomenon). So you need to have a significant absorption edge > somewhere in the neighborhood in order to get an anomalous dispersion > contribution (f') that makes it look like there aer fewer electrons > present. Sorry, I guess I wasn't very clear. I was thinking in terms of the change in f' from the "non-anomalous" atoms (C,N,O) which aren't being used for phasing, or anomalous difference fourier; as opposed to the non-anomalous component of the Se/Mn scattering. Far from the absorbtion edge, this is very small (using the values from atomsf.lib for carbon at Cu and Mo, the difference is 0.015; for oxygen and nitrogen it's larger), but for large numbers of non-anomalous atoms this would accumulate (for 1000 carbons, there would be a cumulative difference of 15). Because this is non-uniform (the change in f' for carbon, nitrogen and oxygen are different), even though it's resolution-independent this wouldn't be dealt with well by a scale factor (at least based on my understanding). I kind of went off on a tangent from the Mn refinement, however... Sorry about that. Pete Pete Meyer Fu Lab BMCB grad student Cornell University
