[chimerax-users] Refinement in ISOLDE failing

Dear everyone I am trying to refine my protein using ISOLDE in ChimeraX which is failing with the following error. "At least one residue in your model does not match any templates in the MD forcefield. This may be due to missing or superfluous atoms, or an unusual residue that has not yet been parameterised. Launching the unparameterised residue widget to help sort this out." The protein contains two heme molecules and Ca ions which obviously is the reason why it is failing. Once these molecules are deleted it runs fine. My question is how to add that specific MD force field for these molecules in order to run the ISOLDE in ChimeraX. Any input would be appreciated. Firdous