QMMM

References: Laino2005, Laino2006

Input for QM/MM calculations. [Edit on GitHub]

Subsections

Keywords

Keyword descriptions

CENTER: enum = EVERY_STEP

Usage: center (EVERY_STEP|SETUP_ONLY|NEVER)

Valid values:

  • EVERY_STEP Re-center every step

  • SETUP_ONLY Center at first step only

  • NEVER Never center

This keyword sets when the QM system is automatically centered. Default is EVERY_STEP. [Edit on GitHub]

CENTER_GRID: logical = F

Usage: grid_center LOGICAL

This keyword specifies whether the QM system is centered in units of the grid spacing. [Edit on GitHub]

CENTER_TYPE: enum = MAX_MINUS_MIN

Usage: center_type (MAX_MINUS_MIN|PBC_AWARE_MAX_MINUS_MIN)

Valid values:

  • MAX_MINUS_MIN Center of box defined by maximum coordinate minus minimum coordinate

  • PBC_AWARE_MAX_MINUS_MIN PBC-aware centering (useful for &QMMM&FORCE_MIXING)

This keyword specifies how to do the QM system centering. [Edit on GitHub]

DELTA_CHARGE: integer = 0

Usage: DELTA_CHARGE q

Additional net charge relative to that specified in DFT section. Used automatically by force mixing [Edit on GitHub]

EPS_MM_RSPACE: real = 1.00000000E-010

Usage: eps_mm_rspace real

Set the threshold for the collocation of the GEEP gaussian functions. this keyword affects only the GAUSS E_COUPLING. [Edit on GitHub]

E_COUPL: enum = NONE

Aliases: QMMM_COUPLING ,ECOUPL

Usage: E_COUPL GAUSS

Valid values:

  • NONE Mechanical coupling (i.e. classical point charge based)

  • COULOMB Using analytical 1/r potential (Coulomb) - not available for GPW/GAPW

  • GAUSS Using fast gaussian expansion of the electrostatic potential (Erf(r/rc)/r) - not available for DFTB.

  • S-WAVE Using fast gaussian expansion of the s-wave electrostatic potential

  • POINT_CHARGE Using quantum mechanics derived point charges interacting with MM charges

Mentions: ⭐QM/MM with Built-in Force Field

Specifies the type of the QM - MM electrostatic coupling. [Edit on GitHub]

INITIAL_TRANSLATION_VECTOR: real[3] = 0.00000000E+000 0.00000000E+000 0.00000000E+000

Usage: initial_translation_vector

This keyword specify the initial translation vector to be applied to the system. [Edit on GitHub]

MM_POTENTIAL_FILE_NAME: string = MM_POTENTIAL

Usage: MM_POTENTIAL_FILE_NAME {filename}

Name of the file containing the potential expansion in gaussians. See the USE_GEEP_LIB keyword. [Edit on GitHub]

NOCOMPATIBILITY: logical = F

Lone keyword: T

Usage: nocompatibility LOGICAL

This keyword disables the compatibility of QM/MM potential between CPMD and CP2K implementations. The compatibility is achieved using an MM potential of the form: Erf[x/rc]/x + (1/rc -2/(pi^1/2*rc))*Exp[-(x/rc)^2]. This keyword has effect only selecting GAUSS E_COUPLING type. [Edit on GitHub]

PARALLEL_SCHEME: enum = ATOM

Usage: parallel_scheme (ATOM|GRID)

Valid values:

  • ATOM parallelizes on atoms. grids replicated. Replication of the grids can be quite expensive memory wise if running on a system with limited memory per core. The grid option may be preferred in this case.

  • GRID parallelizes on grid slices. atoms replicated.

Chooses the parallel_scheme for the long range Potential [Edit on GitHub]

SPHERICAL_CUTOFF: real[2] = -5.29177209E-001 0.00000000E+000 [angstrom]

Usage: SPHERICAL_CUTOFF

Set the spherical cutoff for the QMMM electrostatic interaction. This acts like a charge multiplicative factor dependent on cutoff. For MM atoms farther than the SPHERICAL_CUTOFF(1) their charge is zero. The switch is performed with a smooth function: 0.5*(1-TANH((r-[SPH_CUT(1)-20*SPH_CUT(2)])/(SPH_CUT(2)))). Two values are required: the first one is the distance cutoff. The second one controls the stiffness of the smoothing. [Edit on GitHub]

USE_GEEP_LIB: integer = 0

Usage: use_geep_lib INTEGER

This keyword enables the use of the internal GEEP library to generate the gaussian expansion of the MM potential. Using this keyword there’s no need to provide the MM_POTENTIAL_FILENAME. It expects a number from 2 to 15 (the number of gaussian functions to be used in the expansion. [Edit on GitHub]