$TRUDGE group            (required for RUNTYP=TRUDGE)
 
    This group defines the parameters for a non-gradient
optimization of exponents or the geometry.  The TRUDGE
package is a modified version of the same code from Michel
Dupuis' HONDO 7.0 system, origially written by H.F.King.
Presently the program allows for the optimization of 10
parameters.
 
    Exponent optimization works only for uncontracted
primitives, without enforcing any constraints.  Two
non-symmetry equivalent H atoms would have their p
function exponents optimized separately, and so would two
symmetry equivalent atoms!  A clear case of GIGO.
 
    Geometry optimization works only in HINT internal
coordinates (see $CONTRL and $DATA inputs).  The total
energy of all types of SCF wavefunctions can be optimized,
although this would be extremely stupid as gradient
methods are far more efficient.  The main utility is for
open shell MP2 or CI geometry optimizations, which may
not be done in any other way with GAMESS.  If your run
requires NOSYM=1 in $CONTRL, you must be sure to use only
C1 symmetry in the $DATA input.
 
 
OPTMIZ = a flag to select optimization of either geometry
         or exponents of primitive gaussian functions.
       = BASIS    for basis set optimization.
       = GEOMETRY for geometry optimization (default).
         This means minima search only, there is no saddle
         point capability.
 
NPAR   = number of parameters to be optimized.
 
IEX    = defines the parameters to be optimized.
 
         If OPTMIZ=BASIS, IEX declares the serial number
    of the Gaussian primitives for which the exponents
    will be optimized.
 
         If OPTMIZ=GEOMETRY, IEX define the pointers to
    the HINT internal coordinates which will be optimized.
    (Note that not all internal coordinates have to be
    optimized.) The pointers to the internal coordinates
    are defined as:  (the number of atom on the input
    list)*10 + (the number of internal coordinate for that
    atom).  For each atom, the HINT internal coordinates
    are numbered as 1, 2, and 3 for BOND, ALPHA, and BETA,
    respectively.
 
P  =  Defines the initial values of the parameters to be
      optimized.  You can use this to reset values given
      in $DATA.  If omitted, the $DATA values are used.
      If given here, geometric data must be in Angstroms
      and degrees.
 
A complete example is a TCSCF multireference 6-31G
geometry optimization for methylene,
 $CONTRL SCFTYP=GVB CITYP=GUGA RUNTYP=TRUDGE
         COORD=HINT $END
 $BASIS  GBASIS=N31 NGAUSS=6 $END
 $DATA
Methylene TCSCF+CISD geometry optimization
Cnv 2
 
C    6.     LC  0.00  0.0  0.00  -  O  K
H    1.    PCC  1.00  53.  0.00  +  O  K  I
 $END
 $SCF    NCO=3 NPAIR=1 $END
 $TRUDGE OPTMIZ=GEOMETRY  NPAR=2
         IEX(1)=21,22   P(1)=1.08 $END
 $CIDRT  GROUP=C2V SOCI=.TRUE. NFZC=1 NDOC=3 NVAL=1
         NEXT=-1 $END
using GVB-PP(1), or TCSCF orbitals in the CI.  The starting
bond length is reset to 1.09, while the initial angle will
be 106 (twice 53).  Result after 17 steps is R=1.1283056,
half-angle=51.83377, with a CI energy of -38.9407538472
 
    Note that you may optimize the geometry for an excited
CI state, just specify
          $GUGDIA   NSTATE=5  $END
          $GUGDM    IROOT=3   $END
to find the equilibrium geometry of the third state (of
five total states) of the symmetry implied by your $CIDRT.
 
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