ffsim.UCCSDOpUnrestricted

class ffsim.UCCSDOpUnrestricted(t1, t2, final_orbital_rotation=None, validate=True, rtol=1e-05, atol=1e-08)

Bases: SupportsApplyUnitary, SupportsApproximateEquality

Unrestricted unitary coupled cluster, singles and doubles operator.

UCCSD operator with complex-valued t-amplitudes.

t1

The t1 amplitudes, as a pair of Numpy arrays (t1_a, t1_b) with shapes (nocc_a, nvrt_a) and (nocc_b, nvrt_b).

Type:

tuple[np.ndarray, np.ndarray]

t2

The t2 amplitudes, as a tuple of Numpy arrays (t2_aa, t2_ab, t2_bb) with shapes (nocc_a, nocc_a, nvrt_a, nvrt_a), (nocc_a, nocc_b, nvrt_a, nvrt_b), and (nocc_b, nocc_b, nvrt_b, nvrt_b).

Type:

tuple[np.ndarray, np.ndarray, np.ndarray]

final_orbital_rotation

The optional final orbital rotation, as a Numpy array of shape (2, norb, norb).

Type:

np.ndarray | None

Parameters:

• validate (InitVar) – Whether to validate the operator attributes. Setting this to False skips validation, which is useful if you need to create many instances of this class and are confident that the attributes are valid.

• rtol (InitVar) – Relative numerical tolerance for validation checks.

• atol (InitVar) – Absolute numerical tolerance for validation checks.

Methods

from_parameters(params, *, norb, nelec[, ...])	Initialize the UCCSD operator from a real-valued parameter vector.
n_params(norb, nelec, *[, ...])	Return the number of parameters of an ansatz with given settings.
to_parameters()	Convert the UCCSD operator to a real-valued parameter vector.

Attributes

atol
final_orbital_rotation
norb	The number of spatial orbitals.
rtol
validate
t1
t2