Dear Sir, Thank you all who have replied. It is very nice to have such a wonderful explanation of Anomalous dispersion and Anomalous scattering.
I am sorry to say that SHELXD give me the coordinates with occ >1. It is not. Actually I am aimed to incorporate the phases from MR. During this process an iodine data has been collected. I initially find the substructure with SHELXD and refined it with SHELXE. Than incorporate the coordiantes in PHASER EP where I also incorporate the MR structure also. This give out a pdb file with another atom set where some of occupancies greater than 1. I was just wondering that how the occupancy may get the value > 1 if it is actually. Sincerely Debajyoti Dutta On Wed, 22 Jul 2009 20:10:06 +0530 wrote > >Ian Tickle has just written a definitive answer to your first >question, so I will just comment on questions 2 and 3. > >SHELXD divides the occupancies by the occupancy of the first atom in >the peaklist, so they should not be greater than 1.0. I was not able >to find an example of an occupancy greater than 1.0 in a PDB file >from SHELXD. Assuming that you are using the current version >of SHELXD (2006/3) I would appreciate receiving more details. If you >are using SHELXE for phasing only the RELATIVE occupancies are used >anyway. > >Some useful statistics are printed out by SHELXC when it prepares >the files for SHELXD and SHELXE. If you would like to display these >nicely in graphical form you can use Thomas Schneider's hkl2map GUI >to call SHELXC/D/E (strongly recommended anyway). > >George > >Prof. George M. Sheldrick FRS >Dept. Structural Chemistry, >University of Goettingen, >Tammannstr. 4, >D37077 Goettingen, Germany >Tel. +49-551-39-3021 or -3068 >Fax. +49-551-39-22582 > > >On Wed, 22 Jul 2009, DebajyotiDutta wrote: > >> Dear Sir, >> >> I have very little knowledge about anomalous dispersion method. The thing is >> that I have just started to deal with a case of SAD. I have consulted >> several text books to acquire knowledge about it though I have some queries. >> CCP4BB, I think is the best place to place my questions. >> >> 1.Is there any difference between Anomalous Dispersion and Anomalous >> Scattering? >> >> 2.Sometimes I found that while searching for anomalous scatterer with SHELXD >> which give the coordinates of the scatterer in PDB format with occupancy >> more than 1. Why anomalous occupancy may be more than 1. >> >> 3.I found that there is one plot (FPH FP)/FP Vs Resolution indicate the >> isomorphism but how can I get this plot does SHELX has any option to print >> it. >> >> >> Thank you all for your time and reply to a beginners query in advance. >> >> Sincerely >> Debajyoti Dutta >>
