NPTState

class torch_sim.integrators.npt.NPTState(*, positions, masses, cell, pbc, atomic_numbers, charge=None, spin=None, system_idx=None, _constraints=<factory>, _rng=None, momenta, energy, forces, stress)

Bases: MDState

State information for an NPT system.

This class extends MDState with the stress tensor needed for constant-pressure simulations. Integrator-specific NPT states (e.g., NPTLangevinState, NPTNoseHooverState) inherit from this class and add their own auxiliary variables.

Variables:

stress (torch.Tensor) – Stress tensor [n_systems, n_dim, n_dim]

Parameters:

• positions (Tensor)

• masses (Tensor)

• cell (Tensor)

• pbc (Tensor)

• atomic_numbers (Tensor)

• charge (Tensor | None)

• spin (Tensor | None)

• system_idx (Tensor)

• _constraints (list[Constraint])

• _rng (int | Generator | None)

• momenta (Tensor)

• energy (Tensor)

• forces (Tensor)

• stress (Tensor)