$STATPT group        (for RUNTYP=OPTIMIZE or SADPOINT)                          
    This group controls the search for stationary points.                       
Note that NZVAR in $CONTRL determines if the geometry                           
search is conducted in Cartesian or internal coordinates.                       
METHOD = optimization algorithm selection.  Pick from                           
         NR   Straight Newton-Raphson iterate. This will                        
              attempt to locate the nearest stationary                          
              point, which may be of any order. There                           
              is no steplength control. RUNTYP can be                           
              either OPTIMIZE or SADPOINT                                       
         RFO  Rational Function Optimization. This is                           
              one of the augmented Hessian techniques                           
              where the shift parameter(s) is(are) chosen                       
              by a rational function approximation to                           
              the PES. For SADPOINT searches it involves                        
              two shift parameters. If the calculated                           
              stepsize is larger than DXMAX the step is                         
              simply scaled down to size.                                       
         QA   Quadratic Approximation. This is another                          
              version of an augmented Hessian technique                         
              where the shift parameter is chosen such                          
              that the steplength is equal to DXMAX.                            
              It is completely equivalent to the TRIM                           
              method. (default)                                                 
         SCHLEGEL The quasi-NR optimizer by Schlegel.                           
         CONOPT, CONstrained OPTimization. An algorithm                         
              which can be used for locating TSs.                               
              The starting geometry MUST be a minimum!                          
              The algorithm tries to push the geometry                          
              uphill along a chosen Hessian mode (IFOLOW)                       
              by a series of optimizations on hyperspheres                      
              of increasingly larger radii.                                     
              Note that there currently are no restart                          
              capabilitites for this method, not even                           
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                         
         is punched if NSTEP is exceeded.  The default is                       
         50 steps for a minimum search, but only 20 for                         
         a transition state search, which benefit from                          
         relatively frequent Hessian re-evaluations.                            
      --- the next four control the step size ---                               
DXMAX  = initial trust radius of the step, in Bohr.                             
         For METHOD=RFO, QA, or SCHLEGEL, steps will                            
         be scaled down to this value, if necessary.                            
         (default=0.3 for OPTIMIZE and 0.2 for SADPOINT)                        
         For METHOD=NR, DXMAX is inoperative.                                   
         For METHOD=CONOPT, DXMAX is the step along the                         
         previous two points to increment the hypersphere                       
         radius between constrained optimizations.                              
    the next three apply only to METHOD=RFO or QA:                              
TRUPD  = a flag to allow the trust radius to change as                          
         the geometry search proceeds.  (default=.TRUE.)                        
TRMAX  = maximum permissible value of the trust radius.                         
         (default=0.5 for OPTIMIZE and 0.3 for SADPOINT)                        
TRMIN  = minimum permissible value of the trust radius.                         
     --- the next three control mode following ---                              
IFOLOW = Mode selection switch, for RUNTYP=SADPOINT.                            
         For METHOD=RFO or QA, the mode along which the                         
         energy is maximized, other modes are minimized.                        
         Usually referred to as "eigenvector following".                        
         For METHOD=SCHLEGEL, the mode whose eigenvalue                         
         is (or will be made) negative.  All other                              
         curvatures will be made positive.                                      
         For METHOD=CONOPT, the mode along which the                            
         geometry is initially perturbed from the minima.                       
         (default is 1)                                                         
         In Cartesian coordinates, this variable doesn't                        
         count the six translation and rotation degrees.                        
         Note that the "modes" aren't from mass-weighting.                      
STPT   = flag to indicate whether the initial geometry                          
         is considered a stationary point. If .true.                            
         the initial geometry will be perturbed by                              
         a step along the IFOLOW normal mode with                               
         stepsize STSTEP. (default=.false.)                                     
         The positive direction is taken as the one where                       
         the largest component of the Hessian mode is                           
         positive. If there are more than one largest                           
         component (symmetry), the first is taken as                            
         Note that STPT=.TRUE. has little meaning with                          
         HESS=GUESS as there will be many degenerate                            
STSTEP = Stepsize for jumping off a stationary point.                           
         Using values of 0.05 or more may work better.                          
IFREEZ = array of coordinates to freeze.  These may be                          
         internal or Cartesian coordinates.  For example,                       
         IFREEZ(1)=1,3 freezes the two bond lengths in                          
         the $ZMAT example, which was for a triatomic                           
           $CONTRL NZVAR=3 $END                                                 
           $ZMAT IZMAT(1)=1,1,2,  2,1,2,3,  1,2,3  $END                         
         while optimizing the angle.                                            
         If NZVAR=0, so that this value applies to the                          
         Cartesian coordinates instead, the input of                            
         IFREEZ(1)=4,8 means to freeze the x coordinate                         
         of the 2nd and y coordinate of the 3rd atom.                           
         See also IFZMAT and FVALUE in $ZMAT, and IFCART                        
         below, as IFREEZ does not apply to DLC internals.                      
         In a numerical Hessian run, IFREEZ specifies                           
         Cartesian displacements to be skipped for a                            
         Partial Hessian Analysis.  IFREEZ can pertain to                       
         EFP particles, but only during RUNTYP=HESSIAN,                         
         where the 6 translational and rotational degrees                       
         of freedom of each EFP come AFTER the QM atom                          
         coordinates.  For more information:                                    
         J.D.Head, Int.J.Quantum Chem. 65, 827, 1997                            
         H.Li, J.H.Jensen                                                       
             Theoret. Chem. Acc. 107, 211-219(2002)                             
IFCART = array of Cartesian coordinates to freeze during                        
         a geometry optimization using delocalized internal                     
         coordinates.  This probably works less well than                       
         IFREEZ when it freezes Cartesians.  Only one of                        
         IFREEZ or IFCART may be chosen in a single run.                        
IACTAT = array of "active atoms", which is a complimentary                      
         input to IFREEZ.  Any atom *not* included in the                       
         list has its Cartesian coordinates frozen.  Thus                       
         IACTAT(1)=3,-5,107,144,202,-211 allows 15 atoms,                       
         namely 3-5, 107, 144, and 202-211 to be optimized,                     
         while all other atoms are frozen.  NZVAR in                            
         $CONTRL must be 0 when this option is chosen.                          
IFREEZ and IACTAT are mutually exclusive.  The latter acts                      
by generating a IFREEZ for all atom coordinates not defined                     
as "active", so users can input whichever list is shorter.                      
 --- The next two control the hessian matrix quality ---                        
HESS   = selects the initial hessian matrix.                                    
       = GUESS chooses an initial guess for the hessian.                        
               (default for RUNTYP=OPTIMIZE)                                    
       = READ  causes the hessian to be read from a $HESS                       
               group. (default for RUNTYP=SADPOINT)                             
       = RDAB  reads only the ab initio part of the                             
               hessian, and approximates the effective                          
               fragment blocks.                                                 
       = RDALL reads the full hessian, then converts                            
               any fragment blocks to 6x6 T+R shape.                            
               (this option is seldom used).                                    
       = CALC  compute the hessian, see $FORCE input.                           
IHREP  = the number of steps before the hessian is                              
         recomputed.  If given as 0, the hessian will                           
         be computed only at the initial geometry if                            
         you choose HESS=CALC, and never again.  If                             
         nonzero, the hessian is recalculated every                             
         IHREP steps, with the update formula used on                           
         other steps.  (default=0)                                              
HSSEND = a flag to control automatic hessian evaluation                         
         at the end of a successful geometry search.                            
   --- the next two control the amount of output ---                            
    Let 0 mean the initial geometry, L mean the last                            
    geometry, and all mean every geometry.                                      
    Let INTR mean the internuclear distance matrix.                             
    Let HESS mean the approximation to the hessian.                             
    Note that a directly calculated hessian matrix                              
    will always be punched, NPUN refers only to the                             
    updated hessians used by the quasi-Newton step.                             
NPRT   =  1  Print INTR at all, orbitals at all                                 
          0  Print INTR at all, orbitals at 0+L (default)                       
         -1  Print INTR at all, orbitals never                                  
         -2  Print INTR at 0+L, orbitals never                                  
NPUN   =  3  Punch all orbitals and HESS at all                                 
          2  Punch all orbitals at all                                          
          1  same as 0, plus punch HESS at all                                  
          0  Punch all orbitals at 0+L, otherwise only                          
             occupied orbitals (default)                                        
         -1  Punch occ orbitals at 0+L only                                     
         -2  Never punch orbitals                                               
---- the next parameters control harmonic constraints ---                       
Harmonic constraints can be added to the current geometry                       
by setting ALL the keywords below.  For instance, to                            
harmonically constrain the distance between atom 3 and 12                       
to a distance of 2.0 Angstrom and a force constant of 500                       
kcal/mol, the following example can be used:                                    
   IHMCON(1)=1,3,12  SHMCON(1)=2.0  FHMCON(1)=500.0                             
The default is all zeros which means do not do this.                            
IHMCON = array of coordinates to constrain. The input                           
         is similar to IZMAT in $ZMAT, a code integer,                          
         and the atoms involved in the coordinate.                              
         The code integer may only be 1, for stretches.                         
SHMCON = equilibrium constraint values for the distances                        
         specified by IHMCON, given in Angstrom.                                
FHMCON = array of force constants for the distances                             
         specified by IHMCON, given in kcal/mol.                                
 ---- the following parameters are quite specialized ----                       
PURIFY = a flag to help eliminate the rotational and                            
         translational degrees of freedom from the                              
         initial hessian (and possibly initial gradient).                       
         This is much like the variable of the same name                        
         in $FORCE, and will be relevant only if internal                       
         coordinates are in use.  (default=.FALSE.)                             
PROJCT = a flag to eliminate translation and rotational                         
         degrees of freedom from Cartesian optimizations.                       
         The default is .TRUE. since this normally will                         
         reduce the number of steps, except that this                           
         variable is set false when POSITION=FIXED is                           
         used during EFP runs.                                                  
ITBMAT = number of micro-iterations used to compute the                         
         step in Cartesians which corresponds to the                            
         desired step in internals.  The default is 5.                          
UPHESS = SKIP     do not update Hessian (not recommended)                       
         BFGS     default for OPTIMIZE using RFO or QA                          
         POWELL   default for OPTIMIZE using NR or CONOPT                       
         POWELL   default for SADPOINT                                          
         MSP      mixed Murtagh-Sargent/Powell update                           
         SCHLEGEL only choice for METHOD=SCHLEGEL                               
 ---- NNEG, RMIN, RMAX, RLIM apply only to SCHLEGEL ----                        
NNEG   = The number of negative eigenvalues the force                           
         constant matrix should have. If necessary the                          
         smallest eigenvalues will be reversed. The                             
         default is 0 for RUNTYP=OPTIMIZE, and 1 for                            
RMIN   = Minimum distance threshold. Points whose root                          
         mean square distance from the current point is                         
         less than RMIN are discarded. (default=0.0015)                         
RMAX   = Maximum distance threshold. Points whose root                          
         mean square distance from the current point is                         
         greater than RMAX are discarded. (default=0.1)                         
RLIM   = Linear dependence threshold. Vectors from the                          
         current point to the previous points must not                          
         be colinear.  (default=0.07)                                           
       * * * * * * * * * * * * * * * * * * * * *                                
       See the 'further information' section for                                
       some help with OPTIMIZE and SADPOINT runs                                
       * * * * * * * * * * * * * * * * * * * * *                                

generated on 7/7/2017