6CYANA: grid search - CYANA command

Parameters: tfcut=<real>                   (default: 0.0)
            test

This command performs a grid search for the current fragment (as
defined by the most recent 'grid fragment' command). The grid search
will be done over all torsion angles in the fragment and with the
number of steps per torsion angle given by the variable 'nstep'. If
the cutoff value given by the 'tfcut' for the local, fragment-based
target function is positive, then all conformations with a local
target function value below this cutoff will be considered as
allowed. Otherwise, a conformation will be allowed if no single
restraint violation exceeds the corresponding "soft" cutoff values
defined by the variables soft_upl, soft_lol, soft_vdw, soft_aco, and
soft_cco. Other types of restraints, e.g. residual dipolar couplings
or pseudocontact shifts, cannot be used in grid searches.

To avoid excessive computation times for fragments with many angles
and/or few restraints, the calculation is not started if the expected
number of grid points to be checked (after the evaluation of restraints
that involve a single torsion angle) exceeds the value of the variable
'gridpoints'. Similarly, a grid search is aborted if the estimated
total computation time in seconds exceeds gridtime seconds. If the
number of grid points to be checked (after evaluation of the restraints
that depend on a single dihedral angle) is larger than Nmax, or if
the estimated computation time for the complete grid search exceeds
tmax seconds, the calculation will be stopped.

If the 'test' option is set, the grid search will not be started but
the expected number of grid points to be checked (after evaluation
of the restraints that depend on a single dihedral angle) will be
reported.

The grid search is restricted to angle values that are allowed
according to the standard grid memory, A. The resulting allowed angle
values from the grid search will again be stored in the standard
grid memory.

Further reading:

Guentert et al. J. Biomol. NMR 12, 543-548 (1998).  Guentert et
al. J. Am. Chem. Soc. 111, 3997-4004 (1989).
