Damping: Functions

Collections of damping functions including: - Rational damping (Becke–Johnson) - Zero damping (Chai–Head-Gordon) - Modified zero damping - Optimised power damping - Becke’s Z-damping

class tad_dftd4.damping.functions.Damping

Base interface for damping functions.

This class defines the interface for damping functions used in DFT-D4 calculations. It provides a callable interface that takes the order of the dispersion interaction, pairwise distances, radii, and parameters as input and returns the damping function values.

doi: str | None = None

Digital Object Identifier (DOI) for the damping function.

radius_type: Literal['r4r2', 'rvdw']

Type of radius used in the damping function.

class tad_dftd4.damping.functions.MZeroDamping

Modified zero damping.

REQUIRED_BY_ORDER = {6: ('rs6', 'alp', 'bet'), 8: ('rs8', 'alp', 'bet')}

Required parameters for the damping function.

radius_type: Literal['r4r2', 'rvdw'] = 'rvdw'

Pair-wise van-der-Waals radii.

class tad_dftd4.damping.functions.OptimisedPowerDamping

Optimised-power damping.

REQUIRED_BY_ORDER = {6: ('a1', 'a2', 'bet'), 8: ('a1', 'a2', 'bet')}

Required parameters for the damping function.

radius_type: Literal['r4r2', 'rvdw'] = 'r4r2'

Expectation value of r⁴/r² for the atoms in the system.

class tad_dftd4.damping.functions.RationalDamping

Becke–Johnson rational damping.

\[f^n_{\text{damp}}\left(R_0^{\text{AB}}\right) = \dfrac{R^n_{\text{AB}}}{R^n_{\text{AB}} + \left( a_1 R_0^{\text{AB}} + a_2 \right)^n}\]

REQUIRED_BY_ORDER = {6: ('a1', 'a2'), 8: ('a1', 'a2'), 10: ('a1', 'a2')}

Required parameters for the damping function.

radius_type: Literal['r4r2', 'rvdw'] = 'r4r2'

Expectation value of r⁴/r² for the atoms in the system.

class tad_dftd4.damping.functions.ZeroDamping

Zero damping (also known as Chai–Head-Gordon damping).

\[f^n_{\text{damp}}\left(R^{\text{AB}}\right) = \dfrac{1}{1 + 6 \left( \dfrac{ R^{\text{AB}} }{ R_0^{\text{AB}} } \right)^{-a}} = \dfrac{1}{1 + 6 \left( \dfrac{ R_0^{\text{AB}} }{ R^{\text{AB}} } \right)^{a}}\]

REQUIRED_BY_ORDER = {6: ('rs6', 'alp'), 8: ('rs8', 'alp'), 9: ('rs9', 'alp')}

Required parameters for the damping function.

radius_type: Literal['r4r2', 'rvdw'] = 'rvdw'

Pair-wise van-der-Waals radii.