Rotate specified dihedral to specified value orĀ  by given increment

rotatedihedral crdset <COORDS set> [frame <#>] [name <output set name>] {value <value> | increment <increment>}
{ <mask1> <mask2> <mask3> <mask4> | res <#> type <dih type> } <dih type> = alpha beta gamma delta epsilon zeta nu1 nu2 h1p c2p chin phi psi chip omega

crdset <COORDS set> Coordinates data set to work on. If a TRAJ data set is specified, name must also be specified.
[frame <#>] Frame of the COORDS set to work on.
[name <output set name>] Output COORDS set. If not specified the input COORDS set will be modified.
value <value> Set specified dihedral to given value in degrees.
increment <increment> Increment specified dihedral by increment in degrees.
<mask1> <mask2> <mask3> <mask4> Define dihedral by atom masks. Each mask should only select one atom.
res <#> Rotate dihedral specified by type in residue number <#>.
type <dih type> Dihedral type to rotate in specified residue.

Rotate the specified dihedral in given COORDS set to a target value or by given increment. For example, to set the protein chi dihedral in residue 8 to 35 degrees and write out to a mol2 file:

parm ../tz2.parm7
loadcrd ../ 1 1 name TZ2
rotatedihedral crdset TZ2 value 35 res 8 type chip
crdout TZ2 tz2.rotate.1.mol2