# limitations under the License.
import numpy
import cirq
import openfermion
from openfermioncirq.variational.ansatzes import SplitOperatorTrotterAnsatz
# Construct a Hubbard model Hamiltonian
hubbard_model = openfermion.fermi_hubbard(2, 2, 1., 4.)
hubbard_hamiltonian = openfermion.get_diagonal_coulomb_hamiltonian(
hubbard_model)
# Construct a jellium model Hamiltonian
grid = openfermion.Grid(2, 2, 1.0)
jellium = openfermion.jellium_model(grid, spinless=True, plane_wave=False)
jellium_hamiltonian = openfermion.get_diagonal_coulomb_hamiltonian(jellium)
# Construct a Hamiltonian of ones
ones_hamiltonian = openfermion.DiagonalCoulombHamiltonian(one_body=numpy.ones(
(5, 5)),
two_body=numpy.ones(
(5, 5)))
def test_split_operator_trotter_ansatz_params():
ansatz = SplitOperatorTrotterAnsatz(hubbard_hamiltonian)
assert (set(ansatz.params()) == {
cirq.Symbol(name)
import openfermion
import openfermioncirq
# Set parameters of jellium model.
wigner_seitz_radius = 5. # Radius per electron in Bohr radii.
n_dimensions = 2 # Number of spatial dimensions.
grid_length = 3 # Number of grid points in each dimension.
spinless = True # Whether to include spin degree of freedom or not.
n_electrons = 2 # Number of electrons.
# Figure out length scale based on Wigner-Seitz radius and construct a basis grid.
length_scale = openfermion.wigner_seitz_length_scale(wigner_seitz_radius,
n_electrons, n_dimensions)
grid = openfermion.Grid(n_dimensions, grid_length, length_scale)
# Initialize the model and compute its ground energy in the correct particle number manifold
fermion_hamiltonian = openfermion.jellium_model(grid,
spinless=spinless,
plane_wave=False)
hamiltonian_sparse = openfermion.get_sparse_operator(fermion_hamiltonian)
ground_energy, _ = openfermion.jw_get_ground_state_at_particle_number(
hamiltonian_sparse, n_electrons)
print('The ground energy of the jellium Hamiltonian at {} electrons is {}'.
format(n_electrons, ground_energy))
# Convert to DiagonalCoulombHamiltonian type.
hamiltonian = openfermion.get_diagonal_coulomb_hamiltonian(fermion_hamiltonian)
# Define the objective function
objective = openfermioncirq.HamiltonianObjective(hamiltonian)