MOLPRO

42 GEOMETRY OPTIMIZATION (OPTG) 306
42.1.3 Options to modify convergence criteria
The standard MOLPRO convergency criterion requires the maximum component of the gradient
to be less then 3·10 −4 [a.u.] and the maximum energy change to be less than 1 ·10 −6 [H] or the
maximum component of the gradient to be less then 3·10 −4 [a.u.] and the maximum component
of the step to be less then 3 · 10 −4 [a.u.].
It is also possible to use the convergency criterion of the Gaussian program package. It is
somewhat weaker than the MOLPRO criterion and requires the maximum component of the
gradient to be less then 4.5 · 10 −4 [a.u.] and the root mean square (RMS) of the gradient to be
less then 3 · 10 −4 [a.u.] as well as the maximum component of the optimization step to be less
then 0.0018 [a.u.] and the RMS of the optimization step to be less then 0.0012 [a.u.].
MAXIT=maxit maximum number of optimization cycles. The default is 50.
GRADIENT=thrgrad required accuracy of the optimized gradient. The default is 3 · 10 −4 .
ENERGY=threnerg required accuracy of the optimized energy. The default is 1 · 10 −6 .
STEP=thrstep
BAKER
GAUSSIAN
SRMS=thrsrms
GRMS=thrgrms
FREEZE=thrfreez
convergence threshold for the geometry optimization step. The default
is 3 · 10 −4 .
(logical). Use Baker’s convergency criteria (see J. Baker, J. Comp. Chem.
14,1085 (1993)).
(logical). Use Gaussian convergency criteria.
sets (for Gaussian convergency criterion) the required accuracy of the
RMS of the optimization step. The default is 0.0012.
sets (for Gaussian convergency criterion) the required accuracy of the
RMS of the gradient. The default is 3 · 10 −4 .
Freeze DFT grid and domains in local calculations if the step length
is smaller than thrfreez (default 0.01).
Note: The defaults for the convergence parameters can also be changed by using a global
GTHRESH directive, i.e.
GTHRESH, OPTSTEP=step, OPTGRAD=grad, ENERGY=energy;
42.1.4 Options to specify the optimization space
If the geometry is given as Z-matrix, the default is to optimize the variables on which the Z-
matrix depends. In case of xyz input, always all 3N coordinates are optimized, even if the xyz
input depends on fewer variables. If Cartesian z-matrix input is used, optimization in full space
is only enforced if automatic orientation is requested using the MASS, or CHARGE options on
the ORIENT directive. See opt space in section 42.2.2 for details.
SPACE=ZMAT|3N
OPT3N|3N
ZMAT
Specifies the coordinates to be used in the optimization. Z-matrix
optimization is only possible if the geometry is given as Z-matrix.
(logical). Same as SPACE=3N
(logical). Same as SPACE=ZMAT