43.1.3 Options to modify convergence criteria

The standard MOLPRO convergency criterion requires the maximum component of the gradient to be less then $3 \cdot 10^{-4}$ [a.u.] and the maximum energy change to be less than $1 \cdot 10^{-6}$ [H] or the maximum component of the gradient to be less then $3 \cdot 10^{-4}$ [a.u.] and the maximum component of the step to be less then $3 \cdot 10^{-4}$ [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 $4.5 \cdot 10^{-4}$ [a.u.] and the root mean square (RMS) of the gradient to be less then $3 \cdot 10^{-4}$ [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 $3 \cdot 10^{-4}$.

ENERGY=threnerg

required accuracy of the optimized energy. The default is $1 \cdot 10^{-6}$.

STEP=thrstep

convergence threshold for the geometry optimization step. The default is $3 \cdot 10^{-4}$.

BAKER

(logical). Use Baker's convergency criteria (see J. Baker, J. Comp. Chem. 14,1085 (1993)).

GAUSSIAN

(logical). Use Gaussian convergency criteria.

SRMS=thrsrms

sets (for Gaussian convergency criterion) the required accuracy of the RMS of the optimization step. The default is $0.0012$.

GRMS=thrgrms

sets (for Gaussian convergency criterion) the required accuracy of the RMS of the gradient. The default is $3 \cdot 10^{-4}$.

FREEZE=thrfreez

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;