atom_types section

The atom_types section defines the physical parameters associated with each atom type used in atomistic simulations.

This section is optional, and must be omitted if you want to rely on built-in parameters.

See example for how to structure the input file.

Valid keywords

Keyword	Type	Allowed Values	Default
chi	float or string	>= 0.0	units: a.u.
eta	float or string	> 0.0	units: a.u.
alpha	float or string	> 0.0	units: a.u.
rq	float or string	> 0.0	units: a.u.
rmu	float or string	> 0.0	units: a.u.

Notes

• Each atom type used in the input_geometry must have a corresponding entry here, unless default values are exploited.

• Each atom type defined in input_geometry can define its own atom_type block.

• These parameters define fundamental physical constants for each atomtype:

  • chi: electronegativity [required for fq/fqfmu forcefield]

  • eta: chemical hardness [required for fq/fqfmu forcefield]

  • alpha: polarizability [required for fqfmu forcefield]

  • rq: charge damping radius for gaussian kernel [optional for fq/fqfmu forcefield]

  • rmu: dipole damping radius for gaussian kernel [optional for fq/fqfmu forcefield]

• All values can be provided either as pure float (e.g. 3.2) or with units as strings (e.g. “3.2 a.u.”)

  • chi and eta can be expressed in:

    • a.u. or au

    • eV

  • alpha can be expressed in:

    • a.u. or au

    • nm^3 or nm3

    • ang^3 or ang3 or angstrom3 or angstrom^3

  • rq and rmu can be expressed in:

    • a.u. or au

    • nm or nm

    • ang or angstrom

Example

atom_types:
  Ag:
    chi: 0.0
    eta: 0.483
    alpha: 49.9843
    rq: 1.78756061721763 ang
    rmu: 1.25362081177874 ang