CNS

CNS stands for "Crystallography and NMR System" and is an integrated and full-featured program for the determination and refinement of X-ray crystallographic and NMR structures.

Among its capabilities is simulated annealing molecular dynamics refinement.

• CNS home page

There is a parallelization (OpenMP) source code patch for CNS from Kay dot Diederichs at uni-konstanz dot de. It is now distributed with CNS 1.2 as an alternate download. The parallel version features (roughly) a 2-fold speedup on a 4-core machine for a typical simulated annealing omit map run.

Consider also the more automated and user-friendly PHENIX which, although less complete, is under more active development.

Troubleshooting

It was reported that due to an operating system bug in Mac OSX 10.5.x, the program may crash with

forrtl: severe (174): SIGSEGV, segmentation fault occurred
Image              PC        Routine            Line        Source             
cns_solve          003548DF  Unknown               Unknown  Unknown
cns_solve          00339FBB  Unknown               Unknown  Unknown
cns_solve          000F62EC  Unknown               Unknown  Unknown

Stack trace terminated abnormally.

This may occur if you are running the program with input redirection, but without output redirection, i.e.,

cns < test.inp

and the input file contains one ore more blank lines.

As a possible remedy, try:

cns < test.inp > test.out