ffsim.random.random_molecular_hamiltonian_unrestricted

ffsim.random.random_molecular_hamiltonian_unrestricted(norb, *, one_body_scale=1.0, two_body_scale=1.0, constant_scale=1.0, rank=None, seed=None, dtype=<class 'complex'>)[source]

Sample a random spin-unrestricted molecular Hamiltonian.

The one- and two-body tensors of each spin sector are sampled independently, so the resulting Hamiltonian is not invariant under exchanging the spin alpha and spin beta orbitals.

The alpha-beta two-body tensor is sampled without imposing the symmetry under exchanging its two index pairs that the same-spin tensors possess. This symmetry is not required of the alpha-beta tensor, because the beta-alpha term of the Hamiltonian supplies the transposed contribution. See MolecularHamiltonianUnrestricted.

The scale arguments are applied to every spin sector; see random_molecular_hamiltonian().

Parameters:

  • norb (int) – The number of spatial orbitals.

  • one_body_scale (float) – Multiplies the sampled one-body tensor.

  • two_body_scale (float) – Multiplies the sampled two-body tensor.

  • constant_scale (float) – Multiplies the sampled constant.

  • rank (int | None) – The rank of the sampled two-body tensor. See random_two_body_tensor().

  • seed – A seed to initialize the pseudorandom number generator. Should be a valid input to np.random.default_rng.

  • dtype – The data type to use for the one- and two-body tensors. The constant term will always be of type float.

Return type:

MolecularHamiltonianUnrestricted

Returns:

The sampled spin-unrestricted molecular Hamiltonian.