On Tuesday 01 January 2008 06:40, Mark A Saper wrote: > > Well, I guess one shouldn't change versions of refmac in the middle > of a structure refinement. What are the major differences between . > 0034 and .0066 ? I noted that form factors for the Se atom have > changed dramatically even though I'm using the same " anom formfactor > SE -8.13 5.05 " command. Is this because the program is now using > the wavelength on the .MTZ file ? > > with .0034: > > SE 8.8706 2.4098 5.8196 0.2726 3.9731 15.2372 > 4.3543 43.8163 2.8409
The first coefficient here is wrong. > with .0066: > > SE 17.0006 2.4098 5.8196 0.2726 3.9731 15.2372 > 4.3543 43.8163 -11.7969 These are the values given for a1, b1, ... a4, b4 in Table 6.1.1.4 of International Tables for Crystallography Volume C (1995). The value of c (-11.7969) corresponds to an f' value of -14.6378 (= -11.7969 - 2.8409) This could only be possible at the inflection point of the Se anomalous scattering curve, and only for a beam with a very narrow bandwidth. Current generation beamlines more typically yield an effective f' of -5e to -10e in practice. -- Ethan A Merritt Courier Deliveries: 1959 NE Pacific Dept of Biochemistry Health Sciences Building University of Washington - Seattle WA 98195-7742
