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As far as I know that is true (that is an approximation to the electron density of course. True density is a bit more complex. This approximation works for isolated atoms up to resolution 0.5 or so) if you have infinity resolution. I.e. perfect data. When you have limited resolution then series termination effect needs to be accounted for. The approximation has some problems when you go to infinity resolution and B—> 0 (for example N, you would get something like negative delta function). For limited resolution it should be fine. Regards Garib > On 28 Jun 2018, at 12:50, Aaron Oakley <[log in to unmask]> wrote: > > Dear CCP4ers, > > The Cromer-Mann coefficients ai, bi, c (i = 1 to 4) describing the non-dispersive part of the atomic scattering factor f(s) for a neutral atom as a function of s=(sin theta / lambda) is: > > f(s) = sum(i=1...4) ai*exp(-b*s^2) + c > > Is it correct to interpret this in terms of electron density rho for said atom as a function of distance r from centre: > > rho(r) = sum(i=1…4) a(i) * [4*pi/ (bi + B)]^1.5 * exp[-4*pi^2*r^2 / (bi + B)] > + c * [4*pi / B]^1.5 * exp[-4*pi^2*r^2 / B] > > Where ai, bi and c are the aforementioned Comer-Mann coefficients and B is the temperature factor? > > With thanks, > > a++ > > > Aaron Oakley > Associate Professor > School of Chemistry and Molecular Bioscience | Molecular Horizons | Faculty of Science, Medicine and Health > University of Wollongong NSW 2522 Australia > T +61 2 4221 4347 | F +61 2 4221 4287 > > > > ######################################################################## > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1