CellOptimState

class torch_sim.optimizers.cell_filters.CellOptimState(*, reference_cell, positions, masses, cell, pbc, atomic_numbers, system_idx=None, _constraints=<factory>, _system_extras=<factory>, _atom_extras=<factory>, _rng=None, forces, energy, stress, cell_filter, cell_factor=<factory>, pressure=<factory>, hydrostatic_strain=False, constant_volume=False, frechet_method=None, cell_positions=<factory>, cell_forces=<factory>, cell_masses=<factory>)

Bases: OptimState, DeformGradMixin

State class for cell optimization.

Parameters:

• reference_cell (Tensor)

• positions (Tensor)

• masses (Tensor)

• cell (Tensor)

• pbc (Tensor)

• atomic_numbers (Tensor)

• system_idx (Tensor)

• _constraints (list[Constraint])

• _system_extras (dict[str, Tensor])

• _atom_extras (dict[str, Tensor])

• _rng (int | Generator | None)

• forces (Tensor)

• energy (Tensor)

• stress (Tensor)

• cell_filter (tuple[Callable[[...], None], Callable[[...], None]])

• cell_factor (Tensor)

• pressure (Tensor)

• hydrostatic_strain (bool)

• constant_volume (bool)

• frechet_method (str | None)

• cell_positions (Tensor)

• cell_forces (Tensor)

• cell_masses (Tensor)

deform_grad_forces()

Atomic forces in deformation gradient space, forces @ deform_grad.

Mirrors the transform ASE’s get_forces_unitcellfilter and get_forces_frechet apply to the atomic forces. Equals forces when the cell is undeformed relative to the reference cell.

Returns:

The transformed atomic forces, shape (n_atoms, 3)

Return type:

Tensor

frac_positions()

Atomic positions in the reference cell frame, solve(deform_grad, r).

Returns:

The reference-frame positions, shape (n_atoms, 3)

Return type:

Tensor

positions_from_frac(frac_positions)

Cartesian positions from reference-frame positions, frac @ deform_grad.mT.

Parameters:

frac_positions (Tensor) – Reference-frame positions, shape (n_atoms, 3)

Returns:

The Cartesian positions, shape (n_atoms, 3)

Return type:

Tensor