openfermion.transforms.freeze_orbitals

Fix some orbitals to be occupied and others unoccupied.

openfermion.transforms.freeze_orbitals(
    fermion_operator, occupied, unoccupied=None, prune=True
)

Removes all operators acting on the specified orbitals, and renumbers the remaining orbitals to eliminate unused indices. The sign of each term is modified according to the ladder uperator anti-commutation relations in order to preserve the expectation value of the operator.

occupied A list containing the indices of the orbitals that are to be assumed to be occupied.
unoccupied A list containing the indices of the orbitals that are to be assumed to be unoccupied.