def test_basic_split(self):
"""Test spliting the fermion operators for a simple case.
"""
test_ops = FermionOperator('1 1^', 1.0)
test_ops = normal_ordered(test_ops)
terms, _ = split_openfermion_tensor(test_ops)
self.assertEqual(FermionOperator('1^ 1', -1.0), terms[2])
def test_transform_to_spin_broken(self):
"""Check the conversion between number and spin broken
representations
"""
in_ops = FermionOperator('5^ 7', 1.0)
in_ops += FermionOperator('0^ 2^ 1 3', 2.0)
in_ops += FermionOperator('5^ 6 1 7', 3.0)
ref_ops = FermionOperator('7^ 5', -1.0)
ref_ops += FermionOperator('3^ 2^ 1^ 0^', -2.0)
ref_ops += FermionOperator('7^ 1^ 6 5', 3.0)
test = normal_ordered(transform_to_spin_broken(in_ops))
self.assertEqual(ref_ops, test)
def __init__(
self,
operators: Union[FermionOperator, str],
conserve_spin: bool = True,
e_0: complex = 0.0 + 0.0j,
) -> None:
"""Initializes a SparseHamiltonian.
Args:
operators: Operator with a coefficient in the FermionOperator
format.
conserve_spin: Whether or not to conserve the Sz symmetry.
e_0: Scalar part of the Hamiltonian.
"""
if isinstance(operators, str):
ops = FermionOperator(operators, 1.0)
else:
ops = operators
ops = normal_ordered(ops)
work = ops.terms.pop((), None)
if work is not None:
e_0 += work
super().__init__(e_0=e_0)
self._operators: List[Tuple[complex, List[Tuple[int, int]],
List[Tuple[int, int]]]] = []
self._conserve_spin = conserve_spin
self._rank = 0
for prod in ops.terms:
self._rank = max(self._rank, len(prod))
for oper in ops.get_operators():
(
coeff,
phase,
alpha_block,
beta_block,
) = hamiltonian_utils.gather_nbody_spin_sectors(oper)
alpha_out: List[Tuple[int, int]] = []
beta_out: List[Tuple[int, int]] = []
for alpha in alpha_block:
alpha_out.append((alpha[0] // 2, alpha[1]))
for beta in beta_block:
beta_out.append((beta[0] // 2, beta[1]))
self._operators.append((coeff * phase, alpha_out, beta_out))