# XTB

References: Grimme2017

Parameters needed to set up the xTB methods [Edit on GitHub]

Subsections

- EEQ
- NONBONDED
- PARAMETER
- TBLITE

## Keywords

- CHECK_ATOMIC_CHARGES

- COULOMB_INTERACTION

- COULOMB_LR

- DO_EWALD

- DO_NONBONDED

- EN_SHIFT_TYPE

- EPS_PAIRPOTENTIAL

- GFN_TYPE

- HYDROGEN_STO_NG

- STO_NG

- TB3_INTERACTION

- USE_HALOGEN_CORRECTION

- VARIATIONAL_DIPOLE

- VDW_POTENTIAL

## Keyword descriptions

CHECK_ATOMIC_CHARGES: logical = T

  Lone keyword: `T`

  Usage: CHECK_ATOMIC_CHARGES T

  Mentions: ⭐eXtended Tight Binding

  Stop calculation if atomic charges are outside chemical range. [Edit on GitHub]

COULOMB_INTERACTION: logical = T

  Lone keyword: `T`

  Usage: COULOMB_INTERACTION T

  Mentions: ⭐eXtended Tight Binding

  Use Coulomb interaction terms (electrostatics + TB3); for debug only [Edit on GitHub]

COULOMB_LR: logical = T

  Lone keyword: `T`

  Usage: COULOMB_LR T

  Mentions: ⭐eXtended Tight Binding

  Use Coulomb LR (1/r) interaction terms; for debug only [Edit on GitHub]

DO_EWALD: logical = F

  Lone keyword: `T`

  Usage: DO_EWALD

  Mentions: ⭐eXtended Tight Binding

  Use Ewald type method instead of direct sum for Coulomb interaction [Edit on GitHub]

DO_NONBONDED: logical = F

  Lone keyword: `T`

  Usage: DO_NONBONDED T

  Mentions: ⭐eXtended Tight Binding

  Controls the computation of real-space (short-range) nonbonded interactions as correction to xTB. [Edit on GitHub]

EN_SHIFT_TYPE: string = Molecule

  Usage: EN_SHIFT_TYPE [Select/Molecule/Crystal]

  Shift function for electronegativity in EEQ method. [Select/Molecule/Crystal] Default Select from periodicity. [Edit on GitHub]

EPS_PAIRPOTENTIAL: real = 1.00000000E-010

  Usage: EPS_PAIRPOTENTIAL 1.0E-8

  Accuracy for the repulsive pair potential. [Edit on GitHub]

GFN_TYPE: integer = 1

  Usage: GFN_TYPE 1

  Which GFN xTB method should be used. [Edit on GitHub]

HYDROGEN_STO_NG: integer = 4

  Usage: HYDROGEN_STO_NG 3

  Number of GTOs for Hydrogen basis expansion. [Edit on GitHub]

STO_NG: integer = 6

  Usage: STO_NG 3

  Provides the order of the Slater orbital expansion in GTOs. [Edit on GitHub]

TB3_INTERACTION: logical = T

  Lone keyword: `T`

  Usage: TB3_INTERACTION T

  Mentions: ⭐eXtended Tight Binding

  Use TB3 interaction terms; for debug only [Edit on GitHub]

USE_HALOGEN_CORRECTION: logical = T

  Lone keyword: `T`

  Usage: USE_HALOGEN_CORRECTION T

  Mentions: ⭐eXtended Tight Binding

  Use XB interaction term [Edit on GitHub]

VARIATIONAL_DIPOLE: logical = F

  Lone keyword: `T`

  Usage: VARIATIONAL_DIPOLE T

  gfn0-xTB use dipole definition from energy derivative. [Edit on GitHub]

VDW_POTENTIAL: string

  Usage: VDW_POTENTIAL type

  vdW potential to be used: NONE, DFTD3, DFTD4. Defaults: DFTD3(gfn1), DFTD4(gfn0, gfn2). [Edit on GitHub]