In August there was a discussion entitled "Minimization and mystery nonstandard HIS atom name" and that's the exact problem supposed to have been solved last year. What I did is similar to Jason (http://www.cgl.ucsf.edu/pipermail/chimera-users/2013-August/009069.html), and unfortunately I'm unable to resolve the problem, giving that I'm using chimera 1.8.1 on a Win 7 32G RAM computer. I attach two files, one succeeded till completion while the other one failed early. What I did is simply "Structure editing", next, ok, next, .. Charges of 0.0 were assigned to the unknown atoms 1 model(s) had non-integral total charge Details in reply log No MMTK name for atom "HC1" in standard residue "ALA" Any suggestions to fix the problem is highly appreciated because Chimera is so impressive and I've been using it for many good analyses already. A pity to give up and switch to other programs at this very last stage.