MOLPRO

42 GEOMETRY OPTIMIZATION (OPTG) 312
42.2.4 Defining active geometry parameters (ACTIVE)
ACTIVE,param;
Declares variable name param to be active in the optimization. By default, initially all variables
on which the geometry depends are active; inclusion of an ACTIVE card makes all parameters
inactive unless explicitly declared active (see also INACTIVE).
42.2.5 Defining inactive geometry parameters (INACTIVE)
INACTIVE,param;
Declares variable name param to be inactive in the optimization. If any ACTIVE card appears
in the input, this card is ignored! (see also ACTIVE)
42.2.6 Hessian approximations (HESSIAN)
By default, the MOLPRO geometry optimization utilizes a force field approximation to the hessian
(“Model Hessian”, see R. Lindh, A. Bernhardsson, G. Karlström and P. Malmqvist Chem.
Phys. Lett. 241, 423 (1995)), which speeds up convergence significantly. The Model Hessian is
parameterized for the elements up to the third row. Alternatively, the model Hessian of Schlegel
can be used, or the Hessian can be computed numerically (see also section 42.2.7).
HESSIAN,options
where options can be
MODEL
MODEL=SCHLEGEL
MODEL=VDW
SCHLEGEL
VDW
NOMODEL
NUMERICAL=hstep
Use Lindh’s Model Hessian in optimization (default).
Use Schlegel’s Model Hessian.
Add vdW terms to Lindh’s Model Hessian.
same as MODEL=SCHLEGEL.
same as MODEL=VDW.
Don’t use Model Hessian approximation to the hessian.
Recompute Hessian after hstep iterations. This disables the use of a
model hessian. If hstep=0, the Hessian is only computed in the first
iteration. Default parameters are used for computing the numerical
Hessian, unless modified using options as described for the NUMHESS
directive, see Sect. 42.2.7. Any option valid for the NUMHESS directive
may also follow the NUMERICAL option on the HESSIAN directive.
READ|RECORD|HESSREC=record Read Hessian from given record. If record is not given or
zero, the last computed hessian will be read. See section 42.2.7 for
more details about numerical Hessians.
UPDATE=type
MAXUPD=maxupd
Method used for hessian update. See section 42.2.9 for possibilities
and details.
Max number of hessian updates. The count is reset to zero each time
a hessian is computed.