MOLPRO

42 GEOMETRY OPTIMIZATION (OPTG) 305
42.1 Options
Most parameters can be given as options on the OPTG command line, as described in this section.
Alternatively, directives can be used, which will be described in section 42.2.
42.1.1 Options to select the wavefunction and energy to be optimized
By default, the last computed energy is optimized, and all commands on which the last energy
calculation depends are automatically executed. For certain purposes, e.g., optimization of
counter-poise corrected energies or Davidson corrected energies, the following options can be
used to alter the default behaviour.
STARTCMD=command
PROC=procname
VARIABLE=varname
Specifies a start command. In each geometry optimization step all input
beginning with command to the current OPTG is processed. This
input must not include numerical gradient or Hessian calculations. If
numerical gradients are needed, these will be computed for the final
energy (or specified variable) by OPTG. It is assumed that these commands
have been executed before entering the OPTG program.
specifies a procedure to be executed in each geometry optimization
step. This must define a complete energy calculation (orbital optimization
and correlation treatment), and must not include numerical
gradient of Hessian calculations (numerical gradients will be computed
automatically for the optimized energy or variable). However,
the procedure can include the calculation of analytical gradients, for
instance for counter-poise corrected optimizations in which a linear
combination of several gradient calculations is needed.
Optimize the value of variable varname. This implies numerical gradients.
42.1.2 Options for optimization methods
METHOD=RF|AH|DIIS|QSD|QSTPATH|SRMIN|SRTRANS|STSTEEP
Optimization method to be used. See section 42.2.1 for details.
ROOT=1|2 Minimum search (1, default) or transition state search (2).
DIRECTION=idir
STEPMAX=value
Determines step length and direction in reaction path following, see
section 42.2.16.
Max step length in one optimization step. For more detailed specifications
see section 42.2.12.
TRUST=value Trust ratio for Augmented Hessian method (default 0.5).
AHMAX=value
CUT=value
ROTATE
Maximum step size allowed in the Augmented Hessian procedure.
This refers to the scaled parameter space (default 0.5).
Threshold for ortho-normalization used in conjugate gradient update
of Hessian (default 1.d-3).
(logical). If .true., the Cartesian coordinates are transformed to minimize
rotations (default=.true.)