CYANA Command: minimize
Parameters
- steps=integer
- (default: 100)
- level=integer
- (default: 0)
- flat=integer
- (default: 100)
- angdev=real
- (default: 10.0)
- vdwupdate=integer
- (default: 100)
Description
Performs conjugate gradient minimization steps. Restraints up to the given minimization level are included in the target function. The conjugate gradient minimizer is stopped if within flat minimization steps the target function cannot be reduced by at least 1%. The van der Waals interaction list is updated every vdwupdate steps or each time a torsion angle has changed its value by more than angedev degrees since the last update of the van der Waals interaction list. If the information level is normal or higher, one line of information will be printed out as in the following example from the macro vtfmin:
Minimization (standard strategy):
lev upper lower vdw angle target funct. |grad| #up #f stop
# act # act # act # act begin end end
0 115 13 0 0 313 26 84 9 282.65 0.13 1.8E-2 0 150 maxit
1 271 47 0 0 925 73 84 5 163.09 3.79 0.16 34 150 maxit
2 299 51 0 0 1067 81 84 5 24.71 3.79 0.11 18 150 maxit
3 381 57 0 0 1240 92 84 8 694.27 4.22 0.27 20 116 flat
4 431 74 0 0 1335 90 84 10 21.83 4.47 0.16 9 130 flat
The first column gives the minimization level. Then, there are four times two columns giving the total number of restraints and the number of "active" restraints for the upper limit restraints, the lower limit restraints, the intrinsic van der Waals lower limit restraints, and the angle restraints, respectively. “Active” restraints are those that yield non-vanishing (but often small) contributions to the target function. The next columns give the value of the target function at the beginning and at the end of the minimization step, the norm of the gradient of the target function at the end of the minimization step, the number of updates of the van der Waals contact list, the number of target function evaluations, and a stop code. The following stop codes may occur: gradtl The squared norm of the gradient of the target function is small. maxit The maximal number of target function evaluations, given by the parameter steps, has been exceeded. linmin The maximal number of target function evaluations during the one-dimensional line minimization has been exceeded without decreasing the target function value. nostep The step size during line minimization became too small. uphill The direction of a conjugate gradient minimization step was uphill. const Several conjugate gradient steps did not succeed in decreasing the target function. flat The target function was minimized by less than 1% during the preceding flat iterations. stuck Several attempts to restart the conjugate minimizer after an update of the steric interaction pair list failed.
Normal stop criteria are gradtl, maxit, and flat. Others should occur only rarely.