Hello, I have a 1.2A model with the signs of radiation damage, judged by the negative peaks around the carboxyls (atoms CD, OE1 and OE2) of glutamates probably due to decarboxylation. I wan to refine occupancy of those atoms to account for negative density. What is the proper way of doing it? I tried to set the occupancy for those atoms 0.8 and refine individually. But obviously occupancies for those atoms are individually refined to different values which I dont think is the right way. Is there a way of how to refine occupancies for those atoms so that they remain identical after refinement (say all have 0.6)? Or is there another procedure of how to deal with refinement of radiation damaged side-chains? Any suggestions, please? Thank you Nick