def behler_parrinello(
displacement: DisplacementFn,
species: Array = None,
mlp_sizes: Tuple[int, ...] = (30, 30),
mlp_kwargs: Dict[str, Any] = None,
sym_kwargs: Dict[str, Any] = None,
per_particle: bool = False
) -> Tuple[nn.InitFn, Callable[[PyTree, Array], Array]]:
if sym_kwargs is None:
sym_kwargs = {}
if mlp_kwargs is None:
mlp_kwargs = {'activation': np.tanh}
sym_fn = nn.behler_parrinello_symmetry_functions(displacement, species,
**sym_kwargs)
@hk.without_apply_rng
@hk.transform
def model(R, **kwargs):
embedding_fn = hk.nets.MLP(output_sizes=mlp_sizes + (1, ),
activate_final=False,
name='BPEncoder',
**mlp_kwargs)
embedding_fn = vmap(embedding_fn)
sym = sym_fn(R, **kwargs)
readout = embedding_fn(sym)
if per_particle:
return readout
return np.sum(readout)
return model.init, model.apply
def behler_parrinello(displacement,
species=None,
mlp_sizes=(30, 30),
mlp_kwargs=None,
sym_kwargs=None,
per_particle=False):
if sym_kwargs is None:
sym_kwargs = {}
if mlp_kwargs is None:
mlp_kwargs = {'activation': np.tanh}
sym_fn = nn.behler_parrinello_symmetry_functions(displacement, species,
**sym_kwargs)
@hk.without_apply_rng
@hk.transform
def model(R, **kwargs):
embedding_fn = hk.nets.MLP(output_sizes=mlp_sizes + (1, ),
activate_final=False,
name='BPEncoder',
**mlp_kwargs)
embedding_fn = vmap(embedding_fn)
sym = sym_fn(R, **kwargs)
readout = embedding_fn(sym)
if per_particle:
return readout
return np.sum(readout)
return model.init, model.apply
def test_behler_parrinello_symmetry_functions(self, N_types, N_etas, dtype):
displacement, shift = space.free()
gr = nn.behler_parrinello_symmetry_functions(
displacement,np.array([1, 1, N_types]),
radial_etas=np.array([1e-4/(0.529177 ** 2)] * N_etas, dtype),
angular_etas=np.array([1e-4/(0.529177 ** 2)] * N_etas, dtype),
lambdas=np.array([-1.0] * N_etas, dtype),
zetas=np.array([1.0] * N_etas, dtype),
cutoff_distance=8.0)
R = np.array([[0,0,0], [1,1,1], [1,1,0]], dtype)
gr_out = gr(R)
self.assertAllClose(gr_out.shape, (3, N_etas * (N_types + N_types * (N_types + 1) // 2)))
self.assertAllClose(gr_out[2, 0], dtype(1.885791), rtol=1e-6, atol=1e-6)
