FCIDump#

class FCIDump(num_electrons, hij, hijkl, hij_b=None, hijkl_bb=None, hijkl_ba=None, constant_energy=None, multiplicity=1, orbsym=None, isym=1)[source]#

Bases: object

Qiskit Nature dataclass for representing the FCIDump format.

The FCIDump format is partially defined in Knowles1989.

References

Knowles1989: Peter J. Knowles, Nicholas C. Handy,: A determinant based full configuration interaction program, Computer Physics Communications, Volume 54, Issue 1, 1989, Pages 75-83, ISSN 0010-4655, https://doi.org/10.1016/0010-4655(89)90033-7.

Attributes

constant_energy: float | None = None#: The constant energy comprising (for example) the nuclear repulsion energy and inactive energies.

hij_b: np.ndarray | None = None#: The beta 1-electron integrals.

hijkl_ba: SymmetricTwoBodyIntegrals | None = None#: The beta/alpha 2-electron integrals ordered in chemist’ notation.

hijkl_bb: SymmetricTwoBodyIntegrals | None = None#: The beta/beta 2-electron integrals ordered in chemist’ notation.

isym: int = 1#: The spatial symmetry of the wave function.

multiplicity: int = 1#: The multiplicity.

num_orbitals#: The number of orbitals.

orbsym: Sequence[int] | None = None#: A list of spatial symmetries of the orbitals.

num_electrons: int#: The number of electrons.

hij: np.ndarray#: The alpha 1-electron integrals.

hijkl: SymmetricTwoBodyIntegrals#: The alpha/alpha 2-electron integrals ordered in chemist’ notation.

Methods

classmethod from_file(fcidump)[source]#

Constructs an FCIDump object from a file.

Parameters:: fcidump (str | Path) – Path to the input file.
Returns:: A FCIDump instance.
Return type:: FCIDump

to_file(fcidump)[source]#

Dumps an FCIDump object to a file.

Parameters:

fcidump (str | Path) – Path to the output file.

Raises:

QiskitNatureError – not all beta-spin related matrices are either None or not None.
QiskitNatureError – if the dimensions of the provided integral matrices do not match.