openfermion.ops.representations.get_active_space_integrals

Restricts a molecule at a spatial orbital level to an active space

openfermion.ops.representations.get_active_space_integrals(
    one_body_integrals,
    two_body_integrals,
    occupied_indices=None,
    active_indices=None
)

This active space may be defined by a list of active indices and doubly occupied indices. Note that one_body_integrals and two_body_integrals must be defined n an orthonormal basis set.

one_body_integrals One-body integrals of the target Hamiltonian
two_body_integrals Two-body integrals of the target Hamiltonian
occupied_indices A list of spatial orbital indices indicating which orbitals should be considered doubly occupied.
active_indices A list of spatial orbital indices indicating which orbitals should be considered active.

tuple Tuple with the following entries:

core_constant: Adjustment to constant shift in Hamiltonian from integrating out core orbitals

one_body_integrals_new: one-electron integrals over active space.

two_body_integrals_new: two-electron integrals over active space.