jaxdem.forces.wca

Purely repulsive Weeks-Chandler-Andersen pair interactions.

Classes

WCA([laws])

Weeks-Chandler-Andersen (WCA) purely repulsive Lennard-Jones interaction.

class jaxdem.forces.wca.WCA(laws: tuple[ForceModel, ...] = ())

Bases: ForceModel

Weeks-Chandler-Andersen (WCA) purely repulsive Lennard-Jones interaction.

The model reads the material-pair parameter epsilon_eff[mi, mj].

The model derives the length scale \(\sigma_{ij}\) from the particle radii (as in spring.py):

\[\sigma_{ij} = R_i + R_j\]

Potential (for r < r_c = 2^(1/6) sigma):

U(r) = 4 eps [(sigma/r)^12 - (sigma/r)^6] + eps

else:

U(r) = 0

Force:

F_vec = 24 eps (2 (sigma/r)^12 - (sigma/r)^6) * (1/r^2) * r_ij

search_radii(state: State, system: System) → jax.Array

Conservative search extent for this law’s finite interaction range.

static force(i: int, j: int, pos: jax.Array, state: State, system: System, history: jax.Array, *, advance_history: bool = True, quasistatic: bool = False) → tuple[jax.Array, jax.Array, jax.Array]

static energy(i: int, j: int, pos: jax.Array, state: State, system: System, history: jax.Array) → jax.Array

property required_material_properties: tuple[str, ...]

Names of the material properties this force model needs.

Each name (for example ‘young_eff’ or ‘restitution’) must be present in System.mat_table. Used for validation.