This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. UCSF Chimera is the molecular modeling package being developed at RBVI. Eric Pettersen published a paper describing Chimera in "UCSF Chimera--a visualization system for exploratory research and analysis" (J Comput Chem. 2004 Oct;25(13):1605-12). In addition to molecular models, Chimera also handles volumetric data from microscopy and crystallography. Some of these capabilities are described in "Software extensions to UCSF chimera for interactive visualization of large molecular assemblies" (Structure. 2005 Mar;13(3):473-82). Detailed information and extensive documentation on Chimera may be found at http://www.cgl.ucsf.edu/chimera.