# PARAMETER

Information on and where to find xTB parameters [Edit on GitHub]

## Keywords

- BEN_CONSTANT

- CN_CONSTANTS

- COORDINATION_CUTOFF

- COULOMB_CONSTANTS

- COULOMB_SR_CUT

- COULOMB_SR_EPS

- D3BJ_PARAM

- D3BJ_SCALING

- DISPERSION_PARAMETER_FILE

- DISPERSION_RADIUS

- ENSCALE

- EN_CONSTANTS

- HALOGEN_BINDING

- HUCKEL_CONSTANTS

- KAB_PARAM

- PARAM_FILE_NAME

- PARAM_FILE_PATH

- SRB_PARAMETER

- XB_RADIUS

## Keyword descriptions

BEN_CONSTANT: real = 4.00000000E+000

  Usage: BEN_CONSTANT 4.0

  Scaling parameter for electronegativity correction term. [Edit on GitHub]

CN_CONSTANTS: real[3] = 6.00000000E-003 -3.00000000E-003 -5.00000000E-003

  Usage: CN_CONSTANTS 0.006 -0.003 -0.005

  Scaling parameters for Coordination number correction term. [Edit on GitHub]

COORDINATION_CUTOFF: real = 1.00000000E-006

  Usage: COORDINATION_CUTOFF

  Define cutoff for coordination number calculation [Edit on GitHub]

COULOMB_CONSTANTS: real[2] = 2.00000000E+000 1.50000000E+000

  Usage: COULOMB_CONSTANTS 2.00 1.50

  Scaling parameters for Coulomb interactions (electrons, nuclei). [Edit on GitHub]

COULOMB_SR_CUT: real = 2.00000000E+001

  Usage: COULOMB_SR_CUT 20.0

  Maximum range of short range part of Coulomb interaction. [Edit on GitHub]

COULOMB_SR_EPS: real = 1.00000000E-003

  Usage: COULOMB_SR_EPS 1.E-3

  Cutoff for short range part of Coulomb interaction. [Edit on GitHub]

D3BJ_PARAM: real[2] = 6.30000000E-001 5.00000000E+000

  Usage: D3BJ_PARAM 0.63 5.0

  Becke-Johnson parameters (a1, a2 for the D3 dispersion method. [Edit on GitHub]

D3BJ_SCALING: real[2] = 1.00000000E+000 2.40000000E+000

  Usage: D3BJ_SCALING 1.0 2.4

  Scaling parameters (s6,s8) for the D3 dispersion method. [Edit on GitHub]

DISPERSION_PARAMETER_FILE: string = dftd3.dat

  Usage: DISPERSION_PARAMETER_FILE filename

  Specify file that contains the atomic dispersion parameters for the D3 method [Edit on GitHub]

DISPERSION_RADIUS: real = 1.50000000E+001

  Usage: DISPERSION_RADIUS

  Define radius of dispersion interaction [Edit on GitHub]

ENSCALE: real = 0.00000000E+000

  Usage: ENSCALE 0.01

  Scaling parameter repulsive energy (dEN in exponential). [Edit on GitHub]

EN_CONSTANTS: real[3] = -7.00000000E-003 0.00000000E+000 0.00000000E+000

  Usage: EN_CONSTANTS -0.007 0.000 0.000

  Scaling parameters for electronegativity correction term. [Edit on GitHub]

HALOGEN_BINDING: real[2] = 1.30000000E+000 4.40000000E-001

  Usage: HALOGEN_BINDING 1.30 0.44

  Scaling parameters for electronegativity correction term. [Edit on GitHub]

HUCKEL_CONSTANTS: real[5] = 1.85000000E+000 2.25000000E+000 2.00000000E+000 2.08000000E+000 2.85000000E+000

  Usage: HUCKEL_CONSTANTS 1.85 2.25 2.00 2.08 2.85

  Huckel parameters (s, p, d, sp, 2sH). [Edit on GitHub]

KAB_PARAM: string[ ]

  Keyword can be repeated.

  Usage: KAB_PARAM kind1 kind2 value

  Specifies the specific Kab value for types A and B. [Edit on GitHub]

PARAM_FILE_NAME: string = xTB_parameters

  Usage: PARAM_FILE_NAME filename

  Mentions: ⭐eXtended Tight Binding

  Specify file that contains all xTB default parameters. [Edit on GitHub]

PARAM_FILE_PATH: string

  Usage: PARAM_FILE_PATH pathname

  Mentions: ⭐eXtended Tight Binding

  Specify the directory with the xTB parameter file. [Edit on GitHub]

SRB_PARAMETER: real[6] = -1.29000000E-002 3.48470000E+000 5.09700000E-001 -1.70549806E+000 2.10878369E+000 5.37000000E-002

  Usage: SRB_PARAMETER -0.0129 3.48 0.51 -1.71 2.11 0.0537

  SRB parameters (ksrb, esrb, gscal, c1, c2, shift). [Edit on GitHub]

XB_RADIUS: real = 2.00000000E+001

  Usage: XB_RADIUS 20.0

  Specifies the radius [Bohr] of the XB pair interaction in xTB. [Edit on GitHub]