Swiss-PDBViewer = DeepView
DeepView, formerly known as Swiss-PDBViewer, is a powerful free molecular modeling program by Nicolas Guex, Alexandre Diemand, Manuel C. Peitsch, & Torsten Schwede of the Swiss Institute of Bioinformatics. It is probably the most powerful free modeling program available, and has been for many years. It can be used for structural alignments, homology modeling, mutating molecular models, energy minimization, and many other modeling tasks. For tutorials, step-by-step instructions, and other help, please see the Tutorial and Help at the DeepView Website. The program itself can be downloaded from the official DeepView website.