Hi Fulvio, to better understand this I recommend you to have a look at this article "On atomic displacement parameters (ADP) and their parametrization in PHENIX" here: http://www.phenix-online.org/newsletter/ A quick reply: the target function for ADP refinement is: T = T_xray * wxu_scale * wxu + T_restraints * wu Obviously, by making wxu_smaller you will put more emphasis on restraints. wxu is determined by the program, and wxu_scale is to allow the user to do adjustments (if needed or desired). If you use fix_wxu then the target is T = T_xray * fix_wxu + T_restraints I would play with wxu_scale either manually or let phenix.refine to find a good value automatically (optimize_wxu=True, or whatever is the equivalent in the GUI). There is some information in the manual: http://www.phenix-online.org/documentation/refinement.htm Let me know should you have any questions. Pavel. On 1/25/11 3:36 AM, fulvio saccoccia wrote:

Dear Phenix users and developers, I'm trying to refine a 3 A resolution structure. In order to better understand how can I use wxu_scale and fix_wxu options in phenix.refine, may you explain me their use, since I have a lot of problems with ADPs? In fact, I have big variations between atoms of the same residue. So, is it better to use wxu_scale or to impose fix_wxu to refine the ADPs?

Thanks to all

Fulvio Saccoccia