# LINK

Section can be repeated.

Specify information on the QM/MM link treatment [Edit on GitHub]

Subsections

- ADD_MM_CHARGE
- MOVE_MM_CHARGE

## Keywords

- ALPHA_IMOMM

- CORR_RADIUS

- FIST_SCALE_FACTOR

- LINK_TYPE

- MM_INDEX

- QMMM_SCALE_FACTOR

- QM_INDEX

- QM_KIND

- RADIUS

## Keyword descriptions

ALPHA_IMOMM: real = 1.38000000E+000

  Aliases: ALPHA

  Usage: ALPHA_IMOMM real

  Specifies the scaling factor to be used for projecting the forces on the capping hydrogen in the IMOMM QM/MM link scheme to the MM atom of the link. A good guess can be derived from the bond distances of the forcefield: alpha = r_eq(QM-MM) / r_eq(QM-H). [Edit on GitHub]

CORR_RADIUS: real = [angstrom]

  Usage: CORR_RADIUS real

  Overwrite the specification of the correction radius only for the MM atom involved in the link. Default is to use the same correction radius as for the specified type. [Edit on GitHub]

FIST_SCALE_FACTOR: real = 1.00000000E+000

  Aliases: FIST_CHARGE_SCALE ,FIST_CHARGE_FACTOR ,FIST_SCALE_CHARGE

  Usage: FIST_SCALE_FACTOR real

  Specifies the scaling factor for the MM charge involved in the link QM/MM. This keyword modifies the MM charge in FIST. The modified charge will be used then also for the generation of the QM/MM potential. Default 1.0 i.e. no charge rescaling of the MM atom of the QM/MM link bond. [Edit on GitHub]

LINK_TYPE: enum = IMOMM

  Aliases: LINK ,TYPE ,LTYPE

  Usage: LINK_TYPE char

  Valid values:

  - `IMOMM` Use Integrated Molecular Orbital Molecular Mechanics method

  - `GHO` Use Generalized Hybrid Orbital method

  - `PSEUDO` Use a monovalent pseudo-potential

  Specifies the method to use to treat the defined QM/MM link [Edit on GitHub]

MM_INDEX: integer

  Aliases: MM

  Usage: MM_INDEX integer

  Specifies the index of the MM atom involved in the QM/MM link, Default hydrogen. [Edit on GitHub]

QMMM_SCALE_FACTOR: real = 1.00000000E+000

  Aliases: QMMM_CHARGE_SCALE ,QMMM_CHARGE_FACTOR ,QMMM_SCALE_CHARGE

  Usage: QMMM_SCALE_FACTOR real

  Specifies the scaling factor for the MM charge involved in the link QM/MM. This keyword affects only the QM/MM potential, it doesn’t affect the electrostatic in the classical part of the code. Default 1.0 i.e. no charge rescaling of the MM atom of the QM/MM link bond. [Edit on GitHub]

QM_INDEX: integer

  Aliases: QM

  Usage: QM_INDEX integer

  Specifies the index of the QM atom involved in the QM/MM link [Edit on GitHub]

QM_KIND: string = H

  Usage: QM_KIND char

  Specifies the element of the QM capping atom involved in the QM/MM link [Edit on GitHub]

RADIUS: real = [angstrom]

  Usage: RADIUS real

  Overwrite the specification of the radius only for the MM atom involved in the link. Default is to use the same radius as for the specified type. [Edit on GitHub]