qiskit.chemistry.applications.MolecularGroundStateEnergy

class MolecularGroundStateEnergy(driver, solver=None, transformation=<TransformationType.FULL: 'full'>, qubit_mapping=<QubitMappingType.PARITY: 'parity'>, two_qubit_reduction=True, freeze_core=False, orbital_reduction=None, z2symmetry_reduction=None)

Molecular ground state energy chemistry application

Parameters

• driver (FermionicDriver) – Chemistry driver

• solver (Optional[MinimumEigensolver]) – An Aqua MinimumEigensolver. This can be provided on the constructor or via the solver property, or via the callback on compute_energy()

• transformation (TransformationType) – full or particle_hole

• qubit_mapping (QubitMappingType) – jordan_wigner, parity or bravyi_kitaev

• two_qubit_reduction (bool) – Whether two qubit reduction should be used, when parity mapping only

• freeze_core (bool) – Whether to freeze core orbitals when possible

• orbital_reduction (Optional[List[int]]) – Orbital list to be frozen or removed

• z2symmetry_reduction (Union[str, List[int], None]) – If z2 symmetry reduction should be applied to the qubit operators that are computed. Setting ‘auto’ will use an automatic computation of the correct sector. If from other experiments, with the z2symmetry logic, the sector is known, then the tapering values of that sector can be provided (a list of int of values -1, and 1). The default is None meaning no symmetry reduction is done. See also Hamiltonian which has the core processing behind this class.

__init__(driver, solver=None, transformation=<TransformationType.FULL: 'full'>, qubit_mapping=<QubitMappingType.PARITY: 'parity'>, two_qubit_reduction=True, freeze_core=False, orbital_reduction=None, z2symmetry_reduction=None)

Parameters

• driver (FermionicDriver) – Chemistry driver

• solver (Optional[MinimumEigensolver]) – An Aqua MinimumEigensolver. This can be provided on the constructor or via the solver property, or via the callback on compute_energy()

• transformation (TransformationType) – full or particle_hole

• qubit_mapping (QubitMappingType) – jordan_wigner, parity or bravyi_kitaev

• two_qubit_reduction (bool) – Whether two qubit reduction should be used, when parity mapping only

• freeze_core (bool) – Whether to freeze core orbitals when possible

• orbital_reduction (Optional[List[int]]) – Orbital list to be frozen or removed

• z2symmetry_reduction (Union[str, List[int], None]) – If z2 symmetry reduction should be applied to the qubit operators that are computed. Setting ‘auto’ will use an automatic computation of the correct sector. If from other experiments, with the z2symmetry logic, the sector is known, then the tapering values of that sector can be provided (a list of int of values -1, and 1). The default is None meaning no symmetry reduction is done. See also Hamiltonian which has the core processing behind this class.

Methods

__init__(driver[, solver, transformation, …])	type driver FermionicDriver
compute_energy([callback])	Compute the ground state energy of the molecule that was supplied via the driver
get_default_solver(quantum_instance)	Get the default solver callback that can be used with compute_energy() :type quantum_instance: Union[QuantumInstance, Backend, BaseBackend] :param quantum_instance: A Backend/Quantum Instance for the solver to run on

Attributes

driver	Returns chemistry driver
solver	Returns minimum eigen solver

compute_energy(callback=None)

Compute the ground state energy of the molecule that was supplied via the driver

Parameters

callback (Optional[Callable[[List, int, str, bool, Z2Symmetries], MinimumEigensolver]]) – If not None will be called with the following values num_particles, num_orbitals, qubit_mapping, two_qubit_reduction, z2_symmetries in that order. This information can then be used to setup chemistry specific component(s) that are needed by the chosen MinimumEigensolver. The MinimumEigensolver can then be built and returned from this callback for use as the solver here.

Return type

MolecularGroundStateResult

Returns

A molecular ground state result

Raises

QiskitChemistryError – If no MinimumEigensolver was given and no callback is being used that could supply one instead.

property driver

Returns chemistry driver

Return type

FermionicDriver

static get_default_solver(quantum_instance)

Get the default solver callback that can be used with compute_energy() :type quantum_instance: Union[QuantumInstance, Backend, BaseBackend] :param quantum_instance: A Backend/Quantum Instance for the solver to run on

Return type

Optional[Callable[[List, int, str, bool, Z2Symmetries], MinimumEigensolver]]

Returns

Default solver callback

property solver

Returns minimum eigen solver

Return type

MinimumEigensolver