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Coulomb (cutoff)

Description

The coul_cut_compute_force operator calculates the Coulomb pair potential with a simple real-space cutoff:

\[ E(r) = \frac{1}{4\pi \varepsilon_0 \varepsilon_r} \frac{q_i q_j}{r} \quad \text{for} \quad r<r_c \quad \text{(and } E=0 \text{ for } r\ge r_c\text{)} \]

with \(r_c\) the cutoff and \(\varepsilon_r\) the relative permittivity of the medium.

Parameter Units Description
\(\varepsilon_r\) — Relative dielectric constant of medium
\(r_c\) distance Cutoff radius

YAML syntax

coul_cut_compute_force:
  rcut: VALUE UNITS
  parameters: { epsilon_r: VALUE }
  • VALUE = Physical value of the intended parameter.
  • UNITS = Units of the provided value that will be passed to the conversion helper for internal units conversion.

Usage examples

Systems with a single atomic specy

# Default variant
coul_cut_compute_force:
  parameters: { epsilon_r: 1.0 }
  rcut: 12.0 ang

# Symetric variant
coul_cut_compute_force_symetric:
  parameters: { epsilon_r: 1.0 }
  rcut: 12.0 ang

Systems with multiple atomic species

coul_cut_multi_force:
  rcut: 12.0 ang
  common_parameters: { epsilon_r: 1.0 }
  parameters:
    - { type_a: Na , type_b: Cl , rcut: 12.0 ang , parameters: { } }
    - { type_a: Na , type_b: Na , rcut: 12.0 ang , parameters: { } }