Hi Kenneth, There are recognized advantages to including riding hydrogens during refinement, even at low resolution. Others have written on this better than I could (the following link is a post to the CCP4bb from the archives):
http://www.ysbl.york.ac.uk/ccp4bb/2002/msg01215.html -Andy Torelli -----Original Message----- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Kenneth A. Satyshur Sent: Thursday, January 06, 2011 11:16 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Do carbon scattering include hydrogen Persons of interest: I understood that refinements in refmac of low res structures without hydrogens includes a component of the Hydrogen atom attached to the carbon in the carbon scattering factors. Or is this just if the Hydrogen atoms are in the riding position. If so, why bother to add hydrogens in the riding position. Thanks kas -- Kenneth A. Satyshur, M.S.,Ph.D. Associate Scientist University of Wisconsin Madison, Wisconsin 53706 608-215-5207