CCCP (Coiled-coil Crick Parameterization)
A suite of tools for fitting Crick parameters1,2 for coiled-coil structures and generating structures based on parameters. Contact gevorg.grigoryan at gmail dot com with bug reports and requests.

The Matlab/Octave routines for structure fitting and generation used by CCCP, which operate on CA atoms of the backbone, can be downloaded from here. They are made available under the terms of the GNU General Public License. Inquiries about alternative licensing mechanisms should be directed to Dr. Gevorg Grigoryan. CCCP can also be run on our server, via this interface.

1 F. H. Crick, "The Fourier Transform of a Coiled Coil", Acta Cryst., 6: 685 (1953)
2 G. Grigoryan, W. F. DeGrado, "Probing Designability via a Generalized Model of Helical Bundle Geometry", J. Mol. Biol., 405(4): 1079-1100 (2011)