class UCCSD(num_spatial_orbitals=None, num_particles=None, qubit_mapper=None, *, reps=1, initial_state=None, generalized=False, preserve_spin=True, include_imaginary=False)[source]#

Bases: UCC

The UCCSD Ansatz.

This is a convenience subclass of the UCC ansatz. For more information refer to UCC.

  • num_spatial_orbitals (int | None) -- The number of spatial orbitals.

  • num_particles (tuple[int, int] | None) -- The tuple of the number of alpha- and beta-spin particles.

  • qubit_mapper (QubitMapper | None) -- The QubitMapper which takes care of mapping to a qubit operator.

  • reps (int) -- The number of times to repeat the evolved operators.

  • initial_state (QuantumCircuit | None) -- A QuantumCircuit object to prepend to the circuit.

  • generalized (bool) -- Boolean flag whether or not to use generalized excitations, which ignore the occupation of the spin orbitals. As such, the set of generalized excitations is only determined from the number of spin orbitals and independent from the number of particles.

  • preserve_spin (bool) -- Boolean flag whether or not to preserve the particle spins.

  • include_imaginary (bool) -- Boolean flag which when set to True expands the ansatz to include imaginary parts using twice the number of free parameters.