morse_pair_force

torch_sim.models.morse.morse_pair_force(dr, zi, zj, sigma=1.0, epsilon=5.0, alpha=5.0)

Morse pair force (negative gradient of energy).

F(r) = -2αε exp(-α(r-σ)) (1 - exp(-α(r-σ)))

Parameters:

• dr (Tensor) – Pairwise distances.

• zi (Tensor) – Atomic numbers of first atoms (unused).

• zj (Tensor) – Atomic numbers of second atoms (unused).

• sigma (Tensor | float) – Equilibrium distance. Defaults to 1.0.

• epsilon (Tensor | float) – Well depth. Defaults to 5.0.

• alpha (Tensor | float) – Width parameter. Defaults to 5.0.

Returns:

Pair force magnitudes.

Return type:

Tensor