Hi, I am trying to inspect electron density of X-ray data. I have the PDB-formatted coordinate file a.pdb (not been submitted to PDB yet) and a mtz file (a.mtz). I have downloaded Clipper to Chimera X (1.2.5) running on Window 10. I have opened my a.pdb, and I then tried to open my a.mtz file from the File-Open and I specified the file type with "*.mtz", and opened the a.mtz file, but I then got the error message: "Must specify a structure model to associate with crystallographic data". I know that I was not doing it correctly (e.g. not typing proper commands with correct syntax.). I looked into the description in the URL below. However, I just could not get it work. Any help will be appreciated. Thanks! http://rbvi.ucsf.edu/chimerax/docs/user/commands/open.html#clipper Best wishes, Winston