Hi JD, You can create a text file in the BILD format containing descriptions of arrows. Simply reading it into Chimera creates the objects. The BILD format is quite simple, see: http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/bild.html For example, the following four lines describe two arrows (I also attach this as a separate file for your convenience): .color red .arrow 2 1 2 5 0 0 .color cornflower blue .arrow 0 0 0 1.234 3.066 -8.143 0.5 2.5 0.6 I imagine one could also create the objects directly using a python script, but at least to me, this seems easier. I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. meng@cgl.ucsf.edu UCSF Computer Graphics Lab and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco http://www.cgl.ucsf.edu/home/meng/index.html On May 14, 2007, at 8:30 AM, Jean-Didier Marechal wrote:

I am trying to use chimera to draw arrows of the Normal Modes vectors I previously calculated with charmm. I see different possibilities to provide chimera with the vectors, but how can I draw the arrows?