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OPTKING

Performs geometry optimizations and vibrational frequency analyses.

Optimization Algorithm

CONSECUTIVE_BACKSTEPS

Set number of consecutive backward steps allowed in optimization

  • Type: integer
  • Default: 0

FROZEN_BEND

Specify angles between atoms to be frozen

  • Type: string
  • Default: No Default

FROZEN_DIHEDRAL

Specify dihedral angles between atoms to be frozen

  • Type: string
  • Default: No Default

FROZEN_DISTANCE

Specify distances between atoms to be frozen

  • Type: string
  • Default: No Default

GEOM_MAXITER

Maximum number of geometry optimization steps

  • Type: integer
  • Default: 50

INTERFRAG_STEP_LIMIT

Maximum step size in bohr or radian along an interfragment coordinate

  • Type: double
  • Default: 0.4

INTRAFRAG_STEP_LIMIT

Initial maximum step size in bohr or radian along an internal coordinate

  • Type: double
  • Default: 0.4

INTRAFRAG_STEP_LIMIT_MAX

Upper bound for dynamic trust radius [au]

  • Type: double
  • Default: 1.0

INTRAFRAG_STEP_LIMIT_MIN

Lower bound for dynamic trust radius [au]

  • Type: double
  • Default: 0.001

IRC_DIRECTION

IRC mapping direction

  • Type: string
  • Possible Values: FORWARD, BACKWARD
  • Default: FORWARD

IRC_STEP_SIZE

IRC step size in bohr(amu)^{1/2}.

  • Type: double
  • Default: 0.2

IRC_STOP

Decide when to stop IRC calculations

  • Type: string
  • Possible Values: ASK, STOP, GO
  • Default: STOP

OPT_TYPE

Specifies minimum search, transition-state search, or IRC following

  • Type: string
  • Possible Values: MIN, TS, IRC
  • Default: MIN

RFO_FOLLOW_ROOT

Do follow the initial RFO vector after the first step?

RFO_ROOT

Root for RFO to follow, 0 being lowest (for a minimum)

  • Type: integer
  • Default: 0

STEP_TYPE

Geometry optimization step type, either Newton-Raphson or Rational Function Optimization

  • Type: string
  • Possible Values: RFO, NR, SD, LINESEARCH_STATIC
  • Default: RFO

Convergence Control

FLEXIBLE_G_CONVERGENCE

Even if a user-defined threshold is set, allow for normal, flexible convergence criteria

G_CONVERGENCE

Set of optimization criteria. Specification of any MAX_*_G_CONVERGENCE or RMS_*_G_CONVERGENCE options will append to overwrite the criteria set here unless FLEXIBLE_G_CONVERGENCE is also on. See Table Geometry Convergence for details.

  • Type: string
  • Possible Values: QCHEM, MOLPRO, GAU, GAU_LOOSE, GAU_TIGHT, GAU_VERYTIGHT, TURBOMOLE, CFOUR, NWCHEM_LOOSE
  • Default: QCHEM

MAX_DISP_G_CONVERGENCE

Convergence criterion for geometry optmization: maximum displacement (internal coordinates, atomic units).

MAX_ENERGY_G_CONVERGENCE

Convergence criterion for geometry optmization: maximum energy change.

MAX_FORCE_G_CONVERGENCE

Convergence criterion for geometry optmization: maximum force (internal coordinates, atomic units).

RMS_DISP_G_CONVERGENCE

Convergence criterion for geometry optmization: rms displacement (internal coordinates, atomic units).

RMS_FORCE_G_CONVERGENCE

Convergence criterion for geometry optmization: rms force (internal coordinates, atomic units).

Hessian Update

CART_HESS_READ

Do read Cartesian Hessian? Only for experts - use FULL_HESS_EVERY instead.

FULL_HESS_EVERY

Frequency with which to compute the full Hessian in the course of a geometry optimization. 0 means to compute the initial Hessian only, 1 means recompute every step, and N means recompute every N steps. The default (-1) is to never compute the full Hessian.

  • Type: integer
  • Default: -1

HESS_UPDATE

Hessian update scheme

  • Type: string
  • Possible Values: NONE, BFGS, MS, POWELL, BOFILL
  • Default: BFGS

HESS_UPDATE_LIMIT

Do limit the magnitude of changes caused by the Hessian update?

HESS_UPDATE_LIMIT_MAX

If HESS_UPDATE_LIMIT is true, changes to the Hessian from the update are limited to the larger of HESS_UPDATE_LIMIT_SCALE * (the previous value) and HESS_UPDATE_LIMIT_MAX [au].

  • Type: double
  • Default: 1.00

HESS_UPDATE_LIMIT_SCALE

If HESS_UPDATE_LIMIT is true, changes to the Hessian from the update are limited to the larger of HESS_UPDATE_LIMIT_SCALE * (the previous value) and HESS_UPDATE_LIMIT_MAX [au].

  • Type: double
  • Default: 0.50

HESS_UPDATE_USE_LAST

Number of previous steps to use in Hessian update, 0 uses all

  • Type: integer
  • Default: 1

INTRAFRAG_HESS

Model Hessian to guess intrafragment force constants

  • Type: string
  • Possible Values: FISCHER, SCHLEGEL, SIMPLE, LINDH
  • Default: SCHLEGEL

Fragment/Internal Coordinate Control

ADD_AUXILIARY_BONDS

Do add bond coordinates at nearby atoms for non-bonded systems?

COVALENT_CONNECT

When determining connectivity, a bond is assigned if interatomic distance is less than (this number) * sum of covalent radii.

  • Type: double
  • Default: 1.3

FRAG_MODE

For multi-fragment molecules, treat as single bonded molecule or via interfragment coordinates. A primary difference is that in MULTI mode, the interfragment coordinates are not redundant.

  • Type: string
  • Possible Values: SINGLE, MULTI
  • Default: SINGLE

FREEZE_INTERFRAG

Do freeze all interfragment modes?

FREEZE_INTRAFRAG

Do freeze all fragments rigid?

H_BOND_CONNECT

For now, this is a general maximum distance for the definition of H-bonds

  • Type: double
  • Default: 4.3

INTCOS_GENERATE_EXIT

Do only generate the internal coordinates and then stop?

INTERFRAGMENT_CONNECT

When connecting disparate fragments when frag_mode = SIMPLE, a “bond” is assigned if interatomic distance is less than (this number) * sum of covalent radii. The value is then increased until all the fragments are connected (directly or indirectly).

  • Type: double
  • Default: 1.8

INTERFRAG_DIST_INV

Do use \frac{1}{R_{AB}} for the stretching coordinate between fragments? Otherwise, use R_{AB}.

INTERFRAG_HESS

Model Hessian to guess interfragment force constants

  • Type: string
  • Possible Values: DEFAULT, FISCHER_LIKE
  • Default: DEFAULT

INTERFRAG_MODE

When interfragment coordinates are present, use as reference points either principal axes or fixed linear combinations of atoms.

  • Type: string
  • Possible Values: FIXED, INTERFRAGMENT
  • Default: FIXED

Misc.

FINAL_GEOM_WRITE

Do save and print the geometry from the last projected step at the end of a geometry optimization? Otherwise (and by default), save and print the previous geometry at which was computed the gradient that satisfied the convergence criteria.

INTCO_FIXED_EQ_FORCE_CONSTANT

In constrained optimizations, for internal coordinates with user-specified equilibrium values, this is the force constant (in au) used to apply an additional force to each coordinate. If the user is only concerned to satify the desired constraint, then the user need only ensure that this value is sufficiently large. Alternatively, the user may specify this value to apply a force of a particular magnitude, in which case the given equilibrium value may or may not be reached by the optimization.

  • Type: double
  • Default: 2.0

KEEP_INTCOS

Keep internal coordinate definition file.

LINESEARCH_STATIC_MAX

If doing a static line search, this fixes the largest step, whose largest change in an internal coordinate is set to this value (in au)

  • Type: double
  • Default: 0.100

LINESEARCH_STATIC_MIN

If doing a static line search, this fixes the shortest step, whose largest change in an internal coordinate is set to this value (in au)

  • Type: double
  • Default: 0.001

LINESEARCH_STATIC_N

If doing a static line search, scan this many points.

  • Type: integer
  • Default: 8

TEST_B

Do test B matrix?

TEST_DERIVATIVE_B

Do test derivative B matrix?

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