Hi Alex, The calculation requires parameters for all of the atoms present regardless of whether they are frozen during minimization or not. The frozen atoms still exert forces on the movable atoms. Unfortunately there is a hard limitation on which metal ions can be handled. Possible workarounds have been discussed on chimera-users, for example: <http://www.cgl.ucsf.edu/pipermail/chimera-users/2009-July/004066.html> <http://www.cgl.ucsf.edu/pipermail/chimera-users/2009-March/003682.html> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco http://www.cgl.ucsf.edu/home/meng/index.html On Jul 14, 2009, at 4:56 PM, Alex Gawronski wrote:

Hello,

I used :/!isHet for the "spec" option for "minimize" and I'm still getting "Unable to find GAFF type for #0:155.A@FE " for 101M. I thought this would skip the heme, but I guess not. How can I avoid this error?

Thanks again!

Alex