In any case it will become a Gaussian because presumably the atomic B's are added to the b terms for the density calculation?
-- Ian > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Eleanor Dodson > Sent: 11 October 2007 09:26 > To: [EMAIL PROTECTED] > Cc: [email protected] > Subject: Re: [ccp4bb] atomic FF used in SFALL > > I wrote that - is a constant a Gaussian? Anyway that is how I got 5 - > and it is the > > 9-parameter Cromer-Mann approximation.. > > And Yes - each component is added to the B value to build up > the real space atomic density. > > as you show. > > Eleanor > > > Bernhard Rupp wrote: > > Dear All, > > > > I read in SFALL docu that a "2- or 5-Gaussian" > > approximation for SFs is used - I quote from SFALL docu: > > > > > begin---------------------------------------------------------------- > > a1*exp(-b1*s*s) + a2*exp(-b2*s*s) - 2 Gaussian approximation > > (Agarwal, 1978) > > or as: > > > > a1*exp(-b1*s*s) + a2*exp(-b2*s*s) + a3*exp(-b3*s*s) > > + a4*exp(-b4*s*s) + c > > - 5 Gaussian approximation > > > -------------------------------------------------------------------end > > Note: > > > > 1) The second formula is a 4, not 5 Gaussian approximation - > > Is it the 9-parameter Cromer-Mann approximation? > > > > 2) If so, one would need to convert this (reciprocal space) > scattering > > function into real space e-density when making the map to be FFTed: > > > > rho(r) -> FT -> f(s) <-this f(s) is what the scattering > formula above > > describes > > > > for example from > > > > recip: exp(-Bs*s/4) I would get FT-1 -> real: > > ((4pi/B)**3/2)exp(-4pi**2*r**2/B) > > > > and use that actually to decribe the atom shape in the map > generation. True? > > > > > > Thx, > > > > br > > ----------------------------------------------------------------- > > Bernhard Rupp > > 001 (925) 209-7429 > > +43 (676) 571-0536 > > [EMAIL PROTECTED] > > [EMAIL PROTECTED] > > http://www.ruppweb.org/ > > ----------------------------------------------------------------- > > Every day above ground is a good day. > > ----------------------------------------------------------------- > > > > > > > > Disclaimer This communication is confidential and may contain privileged information intended solely for the named addressee(s). It may not be used or disclosed except for the purpose for which it has been sent. If you are not the intended recipient you must not review, use, disclose, copy, distribute or take any action in reliance upon it. If you have received this communication in error, please notify Astex Therapeutics Ltd by emailing [EMAIL PROTECTED] and destroy all copies of the message and any attached documents. Astex Therapeutics Ltd monitors, controls and protects all its messaging traffic in compliance with its corporate email policy. The Company accepts no liability or responsibility for any onward transmission or use of emails and attachments having left the Astex Therapeutics domain. Unless expressly stated, opinions in this message are those of the individual sender and not of Astex Therapeutics Ltd. The recipient should check this email and any attachments for the presence of computer viruses. Astex Therapeutics Ltd accepts no liability for damage caused by any virus transmitted by this email. E-mail is susceptible to data corruption, interception, unauthorized amendment, and tampering, Astex Therapeutics Ltd only send and receive e-mails on the basis that the Company is not liable for any such alteration or any consequences thereof. Astex Therapeutics Ltd., Registered in England at 436 Cambridge Science Park, Cambridge CB4 0QA under number 3751674
