npt_langevin_isotropic_init¶
- torch_sim.integrators.npt.npt_langevin_isotropic_init(state, model, *, kT, dt, alpha=None, cell_alpha=None, b_tau=None, **_kwargs)[source]¶
Initialize an NPT Langevin state using logarithmic strain coordinate.
The strain coordinate ε = (1/d)·ln(V/V₀) provides well-scaled dynamics where the conjugate force F_ε = d·V·(P_avg - P_ext) is in energy units.
- Parameters:
state (SimState) – Initial SimState
model (ModelInterface) – Model that computes energy, forces, stress
kT (Annotated[float | Tensor, UnitAnnotation(factor=<MetalUnits.mass: 1.0>)]) – Target temperature in energy units
dt (Annotated[float | Tensor, UnitAnnotation(factor=<MetalUnits.time: 98.22694788464062>)]) – Integration timestep
alpha (Annotated[float | Tensor, UnitAnnotation(factor=0.010180505671156725)] | None) – Particle friction coefficient. Defaults to 1/(5·dt).
cell_alpha (Annotated[float | Tensor, UnitAnnotation(factor=0.010180505671156725)] | None) – Cell friction coefficient. Defaults to 1/(30·dt).
b_tau (Annotated[float | Tensor, UnitAnnotation(factor=<MetalUnits.time: 98.22694788464062>)] | None) – Barostat time constant. Defaults to 300·dt.
_kwargs (Any)
- Returns:
Initialized state with ε = 0
- Return type: