$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 manually. 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. (default=0.1) 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. (default=0.05) --- 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 positive. Note that STPT=.TRUE. has little meaning with HESS=GUESS as there will be many degenerate eigenvalues. STSTEP = Stepsize for jumping off a stationary point. Using values of 0.05 or more may work better. (default=0.01) 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. (default=.FALSE.) --- 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 RUNTYP=SADPOINT. 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