XPLOR 3.8 a beta-test version of XPLOR with torsion angle refinement. There is no manual-like for the torsion angle refinement, but you can execute the program and type:

dynamics torsion help

dynamics torsion topology help

Remember to set the MAXTREE parameter. This parameter counts the number of disjoint covalent units present in the simulation. Thus a continuous polypeptide chain count as one tree, but so does a water molecule. So if you have 12 molecules per Asymmetric unit then MAXTREE=12.

There are two example input files: conventional refinement with torsion angle refinement:

/joule2/programs/xplor38/torsion.inp    

/joule2/programs/xplor38/torsion_slow.inp

Remember to remove all heavy atoms, water molecules, single atoms or anything that is not linked to the protein. After reading your PDB and PSF you can delete portions of the model with a statement like this:

     delete selection=(resid 400 ) end

It runs on all the DEC-ALPHAs; the executable is in:

/joule2/programs/xplor38/xplor.exe