High-Performance Computing at the NIH  RSS Feed CCP4 logo   CCP4
(The Collaborative Computational Project Number 4 in Protein
Crystallography) is a suite of separate programs which
communicate via standard data files, rather than all operations
being integrated into one huge program. The programs range from
coordinate file manipulations and dataset management to sequence
alignment and structure validation.  To use the programs the
user must assign input and output files, and run the programs.
Often an output file becomes the input to the next step, and
system parameter substitution may be used to create filenames in
a systematic way. Most crystallographic calculations involve a
series of steps in which no decisions need be made until the
end, and a command file provides an easy way of chaining
calculations.  Standard file formats are defined for the
principal data types used in crystallography: reflection data;
density maps; and atom coordinates. In defining these formats, a
number of trade-offs are made betw