> what is the limit of N in a practical case for the Gaussian approximation.........
The resolution. Less resolution, less terms needed. see Acta papers TenEyck 1977 particularly Agarwal 1978, and the cctbx section in newsletter: http:// <http://cci.lbl.gov/publications/download/iucrcompcomm_jan2004.pdf> cci.lbl.gov/publications/download/iucrcompcomm_jan2004.pdf br _____ From: Jayashankar [mailto:[EMAIL PROTECTED] Sent: Thursday, October 11, 2007 10:54 AM To: [EMAIL PROTECTED] Subject: Re: [ccp4bb] atomic FF used in SFALL On 10/11/07, Bernhard Rupp < <mailto:[EMAIL PROTECTED]> [EMAIL PROTECTED]> wrote: It seems that 5-Gaussian is indeed the accepted technical term for the 9-parameter expansion: Given that a5=c and b5=0, the 5th Gaussian can be a constant. Continuing this reasoning, even a binary mumber can be represented as series of Gaussians.....a=0,b=0; a=1, b=0 This is called 'Gomputing'. Cheers, br -----Original Message----- From: Eleanor Dodson [mailto:[EMAIL PROTECTED] Sent: Thursday, October 11, 2007 1:26 AM To: [EMAIL PROTECTED] Cc: CCP4BB@jiscmail.ac.uk 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 -- S.Jayashankar Research Student Institute for Biophysical Chemistry Hannover Medical School Germany
