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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

FIXED_BEND

Specify angles between atoms to be fixed (eq. value specified)

  • Type: string
  • Default: No Default

FIXED_DIHEDRAL

Specify dihedral angles between atoms to be fixed (eq. value specified)

  • Type: string
  • Default: No Default

FIXED_DISTANCE

Specify distances between atoms to be fixed (eq. value specified)

  • Type: string
  • Default: No Default

FROZEN_BEND

Specify angles between atoms to be frozen (unchanged)

  • Type: string
  • Default: No Default

FROZEN_DIHEDRAL

Specify dihedral angles between atoms to be frozen (unchanged)

  • Type: string
  • Default: No Default

FROZEN_DISTANCE

Specify distances between atoms to be frozen (unchanged)

  • 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.

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?