XTB

References: Grimme2017

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

Subsections

• EEQ
• NONBONDED
• PARAMETER
• TBLITE
• TBLITE_MIXER

Keywords

• CHECK_ATOMIC_CHARGES

• COULOMB_INTERACTION

• COULOMB_LR

• DO_EWALD

• DO_NONBONDED

• EN_SHIFT_TYPE

• EPS_PAIRPOTENTIAL

• GFN_TYPE

• HYDROGEN_STO_NG

• SCC_MIXER

• 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

Deprecated debug override for the xTB Ewald treatment. By default the setting is inferred from SUBSYS/CELL/PERIODIC. If set to TRUE for CP2K-internal xTB, the DFT/POISSON section must use a periodic Poisson solver. For CP2K/tblite, the periodic long-range treatment is performed inside tblite. [Edit on GitHub]

Warning

The keyword DO_EWALD is deprecated and may be removed in a future version.

Use SUBSYS/CELL/PERIODIC to select periodicity. DO_EWALD is retained only as a debug override for the CP2K-internal xTB Ewald path.

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: enum = 1

Usage: GFN_TYPE (0|1|TBLITE)

Valid values:

• 0 Use the CP2K-internal GFN0-xTB implementation.

• 1 Use the CP2K-internal GFN1-xTB implementation.

• TBLITE Use the CP2K/tblite backend; requires XTB/TBLITE.

Selects the xTB backend. GFN_TYPE 1 uses the CP2K-internal GFN1-xTB implementation. GFN_TYPE 0 uses the CP2K-internal GFN0-xTB implementation, which has no SCC variables to mix, so XTB/SCC_MIXER AUTO is treated as NONE. GFN_TYPE TBLITE uses the tblite backend and requires an XTB/TBLITE section, where the actual tblite method is selected. [Edit on GitHub]

HYDROGEN_STO_NG: integer = 4

Usage: HYDROGEN_STO_NG 3

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

SCC_MIXER: enum = AUTO

Usage: SCC_MIXER (AUTO|TBLITE|CP2K|NONE)

Valid values:

• AUTO Default method-dependent choice.

• TBLITE Use the tblite modified Broyden SCC mixer.

• CP2K Use CP2K charge mixing for SCC variables.

• NONE Do not mix SCC variables; for debugging.

Selects the SCC variable mixer for xTB calculations. AUTO is treated as NONE for CP2K-internal GFN0-xTB, keeps the CP2K charge mixer for CP2K-internal GFN1-xTB, and uses tblite’s native SCC mixer for XTB/GFN_TYPE TBLITE. The SCC variables are the model populations and, where required by the selected method, atomic multipoles that feed the self-consistent xTB potential. TBLITE uses tblite’s modified Broyden mixer for those variables inside the CP2K SCF cycle. CP2K maps the variables onto CP2K’s charge-mixing infrastructure. When TBLITE is active, the native SCC convergence follows XTB/TBLITE/ACCURACY and the tblite-side SCC update limit follows TBLITE_MIXER/ITERATIONS. If SCC_MIXER is explicitly set to TBLITE, CP2K also sets DFT/SCF/MAX_SCF to TBLITE_MIXER/ITERATIONS. With SCC_MIXER AUTO or CP2K, MAX_SCF keeps its normal CP2K meaning. With QS/LS_SCF, explicit SCC_MIXER settings are reset to NONE internally and CP2K emits a warning; LS_SCF controls the density-matrix optimization. When CP2K is active, convergence follows the normal CP2K SCF controls, in particular DFT/SCF/EPS_SCF and DFT/SCF/MIXING. For GFN2/tblite, the CP2K mixer acts on the full SCC-variable set: shell charges plus atomic dipole and quadrupole variables. CP2K-internal GFN0-xTB has no SCC variables to mix, so AUTO and NONE are equivalent there and explicit CP2K or TBLITE mixer choices are reset to NONE. For CP2K-internal GFN1 and DFTB/DFTB3, the SCC variables are only charge or shell-charge like. The initial SCC variables are seeded from CP2K’s current density, so DFT/SCF/SCF_GUESS and DFT/WFN_RESTART_FILE_NAME define the starting point. NONE performs direct updates without mixing and is intended for debugging, since it can be unstable. [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]