MOLPRO

42 GEOMETRY OPTIMIZATION (OPTG) 314
SYMM
CART
UNIQUE
Use symmetric displacement coordinates (default). This
is the only recommended option.
Use 3N cartesian displacements (not recommended). This
requires many more energy calculations than necessary
and does not preserve the molecular symmetry.
Use symmetry-unique cartesian displacements (not recommended)
CALC=icalc
THRESH=thresh
Note that the displacement type for gradient and hessian must be the
same.
icalc=0: Recalculate the complete Hessian matrix numerically after
each hstep optimization steps (default).
icalc=1: Recalculate selected Hessian matrix elements if the relative
deviation of this element before and after update (see UPDATE, section
42.2.9) is larger than thresh. If thresh is not specified, a default
value of thresh = 0.05 (i.e. a maximum deviation of 5%) is used.
icalc=2: Recalculate complete Hessian matrix if the RMS deviation
of the Hessian matrix before and after update is larger than thresh. If
thresh is not specified a default value of
Threshold for partial or dynamical update of hessian, see above
42.2.8 Hessian elements (HESSELEM)
HESSELEM,value, active1,active2,. . .
sets the starting value for hessian matrix element between active variables active1, active2 to
value. If active2 is omitted it defaults to active1 (diagonal element). As many HESSELEM
directives as needed may be given.
42.2.9 Hessian update (UPDATE)
UPDATE,[TYPE=]type,MAX=maxupd
This directive chooses the update type and limits the number of points used for the hessian
update to maxupd. The default number of steps used in hessian update procedures is 5. If there
are symmetry constraint in the coordinates of the optimization, the default number may be lower
than five.
In minimizations type may be
BFGS
IBFGS
CGRD
NONE
Use BFGS update of hessian (default).
Use BFGS update of the inverse hessian.
Use Conjugate Gradient update (see also CUT,TRUST).
Don’t do any update.
In transition state optimizations type may be
PMS
POWELL
MS
NONE
Combined Powell/Murtagh-Sargent update of hessian (default).
Use Powell’s update of the hessian.
Use update procedure of Murtagh and Sargent.
Don’t do any update.