The question about Fourier transformation ripples has a straightforward
answer in a fairly typical situation:
A) data are collected to the resolution limit of diffraction,
B) phases are uniform in quality across the resolution range, which is
equivalent to R-free being uniform with respect to resolution within a
factor of 2 or so,
C) maps are not sharpened.
The ripples originate from not including unobserved structure factors. The
intensity of diffraction decreases rapidly past the measurability limit,
so, in the above situation, the unobserved diffraction contributes very
little. Consequently, the answer is that typically one should not see
Ripples should not be confused with the effect of electron density maps
being smoothed by vibrations and other forms of disorder.
> Dear All, Hi. I was asked in a manuscript revision to discuss
> about the possible effects of Fourier transformation ripples on the
> crystallographic results. Specifically, the reviewers question whether
> ripples may affect on the electron density around heavy metal center which
> has a Mo-S-As connection. From which angle or in which way this problem
> should be addressed most convincingly ? Thank you for any
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