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There is also another paper on this that may be useful... Acta Cryst. (2005). D61, 67-74. Correction of X-ray intensities from single crystals containing lattice-translocation defects. J Wang et al. Regards -----Original Message----- From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of [log in to unmask] Sent: Monday, January 26, 2009 6:04 AM To: [log in to unmask] Subject: Re: [ccp4bb] more on lattice translocation defects Dear Laurie, For copyright reasons, I would suggest that you ask the authors for a reprint or pdf. They can legally do it. Concerning lattice translocation defects, as I see it, it means that neighboring layers in a crystal are sometimes translated in one direction, sometimes in another direction. These maybe an integral part of the unit cell (1/2 or 1/3 etc.) as Zhu et al. seem to have, or random values (e.g. 0.32, 0.49). This can lead to several bizarre effects in the diffraction pattern: -if the defects occur frequently, this leads to small coherent domains, which leads to smeared spots. However, spots for which these domains cancel out, stay sharp. As a result, the diffraction pattern shows a mixture of sharp and smeared spots. -The self patterson shows strong peaks for both translations. However, since the translations occur in different unit cells, there are no corresponding cross peaks. -If the translation is almost an integral part of the unit cell, one sees a modulation. E.g. if the translation is 0.45, one sees extinctions for odd h, k or l indexes if the index is around 0, extinctions for even indexes if the index is around 10, extinctions for odd indexes if the index around 20 etc. Best regards, Herman -----Original Message----- From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Laurie Betts Sent: Sunday, January 25, 2009 4:57 PM To: [log in to unmask] Subject: [ccp4bb] more on lattice translocation defects May I inquire if someone has a copy of Zhu et. al. (Acta Cryst. D. 2008 D64, 843-850) that might be posted somewhere free? I don't have subscription to Acta Cryst D and this one is possibly a problem I have in a structure and I don't understand what it means exactly. Or if someone can give a definition in terms that is simple (for my simple mind). Thanks -- Laurie Betts X-ray Crystallography Facility Manager Department of Structural Biology University of Pittsburgh 1050 BST3 3501 Fifth Ave Pittsburgh, PA 15260 412-383-5839