MOLPRO

42 GEOMETRY OPTIMIZATION (OPTG) 317
42.2.16 Reaction path following options (OPTION)
OPTION,key=param;
where key can be
IDIR
STPTOL
SLMAX
If starting at a transition state (or near a transition state) determine
where to take the first step. If IDIR=0 is chosen, the first step will be
towards the transition state. This is the default. If IDIR=1 is given
in the input the first optimization step will be along the ”transition
vector” i.e. the hessian eigenvector to the smallest eigenvalue which
points down towards the minimum. If using a larger IDIR parameter,
the first step will be larger; if using a negative value, the first step will
be in the opposite direction.
If using an updated hessian matrix, this parameter determines what
update to take. If the step size between two subsequent points on
which the steepest decent lines are puzzled together is smaller than
stptol (i.e. if we are close to a minimum) the BFGS update is used,
otherwise it is Powell update. The default value of stptol is 1.d − 6.
This option is only valid with the old version of the reaction path following
algorithm (i.e. METHOD,SRSTEEP). In this algorithm slmax
determines the frequency of the recalculation of the numerical hessian.
If the total step size of the last steps exceeds slmax the hessian
will be recalculated, otherwise it will be updated. By default slmax is
two times the maximum step size of the optimization step steplength
(see STEP section 42.2.12). If you are using METHOD,QSD, the
SLMAX option is obsolete and the NUMHES command (see above)
should be used instead.
42.2.17 Optimizing energy variables (VARIABLE)
VARIABLE,name;
Defines a variable name which holds the energy value to be optimized in using finite differences.
By default, this is ENERGY(1) as set by the most recent program. Other variables which can
be used are
ENERGY(i) holds last energy for state i.
ENERGR(i) holds last reference energy for state i.
ENERGD(i) holds last Davidson corrected energy for state i.
ENERGP(i) holds last Pople corrected energy for state i.
ENERGC
ENERGT(1)
ENERGT(2)
ENERGT(3)
holds CCSD (QCI, BCCD) energy in CCSD(T) [QCI(T), BCCD(T)]
calculations (single state optimization).
holds CCSD(T) energy in CCSD(T) calculations (single state)
holds CCSD[T] energy in CCSD(T) calculations (single state).
holds CCSD-T energy in CCSD(T) calculations (single state).