Hi Miguel, Thanks for the clarification. I agree that it is important to get just the contacting chains, not the whole asymmetric units, and that both crystal symmetries and unit cell translations need to be considered. The basic code to achieve this is already in Chimera so it should not be difficult to add. The needed routines are used by the "crystal contacts" experimental plugin http://www.cgl.ucsf.edu/chimera/experimental/crystal_contacts/clashes.html although that tool works at the level of whole asymmetric units. Some adaptations of that code would allow it to instead consider individual chains and display all atoms of each chains instead of a single sphere for each chain. I'll let you know when I have written code you can try. Tom