$OPTFMO group              (relevant if RUNTYP=OPTFMO)
 
     This group controls the search for stationary points
using optimizers developed for the Fragment Molecular
Orbital (FMO) method. There is no restriction on the number
of atoms in the molecule, whereas optimising FMO with
standard optimizers (RUNTYP=OPTIMIZE) has a restriction to
2000 atoms (unless you rebuild your GAMESS appropriately).
OPTFMO runs may be restarted by providing the updated
coordinates in $FMOXYZ and, optionally, optimization
restart data (punched out for each step) in $OPTRST (the
data differs for each method).
 
METHOD = optimization method
         STEEP  steepest descent
         CG     conjugate gradient
         LBFGS  approximate BFGS numeric updates of the
                inverse Hessian, that do not require
                explicitly storing that matrix.
         HSSUPD numeric updates of the inverse Hessian
         Default: HSSUPD.
 
HESS   = initial inverse Hessian for METHOD=HSSUPD
         GUESS diagonal guess of 3
         READ  read from F38 (advanced option)
         Default: GUESS.
 
UPDATE = inverse Hessian update scheme for METHOD=HSSUPD
         BFGS Broyden-Fletcher-Goldfarb-Shanno
         DFP  Davidon-Fletcher-Powell
         Default: BFGS.
 
OPTTOL = gradient convergence tolerance, in Hartree/Bohr.
         Convergence of a geometry search requires the
         largest component of the gradient to be less
         than OPTTOL, and the root mean square gradient
         less than 1/3 of OPTTOL.  (default=0.0001)
 
NSTEP  = maximum number of steps to take.  Restart data
         are punched at each step. (default=200)
 
IFREEZ = array of coords to freeze during optimization.
         The usage is the same as for the similar option in
         $STATPT.
 
IACTAT = array of active (not frozen) atoms in geometry
         optimizations, see $STATPT for its description.
         IACTAT(1)=-1 has a special meaning: freeze all
         atoms during a cell optimization with PBC.
         Note that in reality only fractional coordinates
         of atoms are frozen, and the absolute values of
         coordinates do change.
 
STEP   = initial step factor. This multiplies the gradient
         to prevent large steps. The values of 0.1-0.2 are
         considered useful in the vicinity of minimum, and
         0.5-1.0 is probably OK at the start. (default: 1)
 
STPMIN = the minimum permitted value of dynamically chosen
         STEP size (see STPFAC). (default: 0)
 
STPMAX = the maximum permitted value of dynamically chosen
         STEP size (see STPFAC). (default: 1)
 
STPFAC = Dynamic adjustment of STEP. If the energy goes
         down considerably, the new STEP is set to the old
         STEP multiplied by 1/STPFAC, if the energy goes up
         significantly, STEP is set to STEP*STPFAC, both
         constrained by STPMIN and STPMAX.  The default is
         1, which means do not use dynamic adjustment. The
         value 0.9 may be useful if dynamically adjusted
         steps are desired.
 
NPRICO = Print coordinates every NPRICO optimization steps
         to reduce the output file.
         (default: 1)
 
IREST  = 0 do not write restart data
         1 the opposite
         The "restart data" are internal arrays needed for
         optimization (excluding the coordinates).
         (default: 0)
 
NFGD   = the number of fragments, must be the same as NFRAG
         in $FMO. For technical reasons, must be set here
         redundantly if using DDI storage of F40, for example,
         if MODIO=3072 is set or if MODPAR=512/1024 in $FMOPRP.
         A job will be aborted if NFGD is too small.
         (default: 0)
 
MAXNAT = the maximum number of atoms per fragment (including
         extra boundary atoms). If set, one file will be
         replaced by operations in memory (DFTB only).
         It is permissible to use an upper bound, if one is too
         lazy to count exactly.
         (default: 0)