Hi Elaine (I think!), I know there is a measure angle feature in Chimera. I have been using this to define metal ligand geometries in our protein structures (for example, distinguishing between square pyramidal and trigonal bypramidal geometries). Maybe if there is enough interest, this could be an automated feature in the future where a metal ion is selected and then all of the ligands and angles are automatically displayed along with an assigned geometry. We've been using the following reference for assigning them. Just a suggestion! Many thanks, Walt -- Walter Fast, Ph.D. Assistant Professor The University of Texas at Austin College of Pharmacy The Division of Medicinal Chemistry Phone: (512) 232-4000 Fax: (512) 232-2606 Lab: (512) 471-5839 Email: WaltFast@mail.utexas.edu http://www.utexas.edu/pharmacy/divisions/medicinalchem/faculty/fast.html