[phenixbb] how to define a molecule in two rigid_body

Dear Colleagues, First, I would say sorry to bother your guys at Friday evening. :) I have a molecule which has two rings connected by a single bond. I would like this two rings freely rotate around the single bond, but keep each ring conformation fixed (as there are sidechains connected to each ring). Could you help me do this rigid_body definition, or suggest a better idea to do so in phenix? Regards and Thanks! Charles Chen. %%%%%%%%%%%%%%%%%%%%% University of Pittsburgh School of Medicine Department of Aneshesiology %%%%%%%%%%%%%%%%%%%%%