def test_inverse_fourier_transform_2d(self):
grid = Grid(dimensions=2, scale=1.5, length=3)
spinless = True
geometry = [('H', (0, 0)), ('H', (0.5, 0.8))]
h_plane_wave = plane_wave_hamiltonian(grid, geometry, spinless, True)
h_dual_basis = plane_wave_hamiltonian(grid, geometry, spinless, False)
h_dual_basis_t = inverse_fourier_transform(h_dual_basis, grid, spinless)
self.assertEqual(normal_ordered(h_dual_basis_t),
normal_ordered(h_plane_wave))
def test_fourier_transform(self):
grid = Grid(dimensions=1, scale=1.5, length=3)
spinless_set = [True, False]
geometry = [('H', (0,)), ('H', (0.5,))]
for spinless in spinless_set:
h_plane_wave = plane_wave_hamiltonian(
grid, geometry, spinless, True)
h_dual_basis = plane_wave_hamiltonian(
grid, geometry, spinless, False)
h_plane_wave_t = fourier_transform(h_plane_wave, grid, spinless)
self.assertTrue(normal_ordered(h_plane_wave_t) ==
normal_ordered(h_dual_basis))
def test_inverse_fourier_transform_1d(self):
grid = Grid(dimensions=1, scale=1.5, length=4)
spinless_set = [True, False]
geometry = [('H', (0, )), ('H', (0.5, ))]
for spinless in spinless_set:
h_plane_wave = plane_wave_hamiltonian(grid, geometry, spinless,
True)
h_dual_basis = plane_wave_hamiltonian(grid, geometry, spinless,
False)
h_dual_basis_t = inverse_fourier_transform(h_dual_basis, grid,
spinless)
self.assertEqual(normal_ordered(h_dual_basis_t),
normal_ordered(h_plane_wave))
def test_fourier_transform(self):
for length in [2, 3]:
grid = Grid(dimensions=1, scale=1.5, length=length)
spinless_set = [True, False]
geometry = [('H', (0.1,)), ('H', (0.5,))]
for spinless in spinless_set:
h_plane_wave = plane_wave_hamiltonian(grid, geometry, spinless,
True)
h_dual_basis = plane_wave_hamiltonian(grid, geometry, spinless,
False)
h_plane_wave_t = fourier_transform(h_plane_wave, grid, spinless)
self.assertEqual(normal_ordered(h_plane_wave_t),
normal_ordered(h_dual_basis))
# Verify that all 3 are Hermitian
plane_wave_operator = get_sparse_operator(h_plane_wave)
dual_operator = get_sparse_operator(h_dual_basis)
plane_wave_t_operator = get_sparse_operator(h_plane_wave_t)
self.assertTrue(is_hermitian(plane_wave_operator))
self.assertTrue(is_hermitian(dual_operator))
self.assertTrue(is_hermitian(plane_wave_t_operator))
def dual_basis_hamiltonian(n_dimensions,
system_size,
plane_wave=False,
spinless=True):
"""Return the plane wave dual basis hamiltonian with the given parameters.
Returns: the Hamiltonian as a normal-ordered FermionOperator.
Args:
n_dimensions (int): The number of dimensions in the system.
system_size (int): The side length along each dimension.
plane_wave (bool): Whether the system is in the plane wave basis.
spinless (bool): Whether the system is spinless.
Notes:
Follows Eq. 10 of https://arxiv.org/pdf/1706.00023.pdf.
"""
grid = Grid(n_dimensions, length=system_size, scale=1.0 * system_size)
hamiltonian = plane_wave_hamiltonian(grid,
spinless=spinless,
plane_wave=plane_wave)
return normal_ordered(hamiltonian)
def __init__(self, a=7.72, n=3, n_active_el=2, n_active_orb=4):
self.a = a
self.n = n
self.n_active_el = n_active_el
self.n_active_orb = n_active_orb
self.N_units = 4
self.opt_energy = None
self.opt_amplitudes = None
species_a = 'H'
species_b = 'Li'
# Construct a fermion Hamiltonian
grid = Grid(3, self.n, self.a)
geometry = [(species_a, (0, 0, 0)), (species_a, (0, 0.5, 0.5)),
(species_a, (0.5, 0, 0.5)), (species_a, (0.5, 0.5, 0)),
(species_b, (0.5, 0.5, 0.5)), (species_b, (0.5, 0, 0)),
(species_b, (0, 0.5, 0)), (species_b, (0, 0, 0.5))]
self.fermion_hamiltonian = plane_wave_hamiltonian(
grid,
geometry=geometry,
spinless=False,
plane_wave=False,
include_constant=False,
e_cutoff=None)
# Freeze specified orbitals
n_qubits = 2 * n * n * n
n_electrons = 4 * 3 + 4 * 1
# Determine the indices of occupied orbitals to be frozen
if self.n == 3:
to_fill = ((1, 1, 1), (0, 1, 1), (2, 1, 1), (1, 0, 1), (1, 2, 1),
(1, 1, 0), (1, 1, 2), (0, 0, 1))
else:
to_fill = range(n_electrons - self.n_active_el)
to_fill_ids = []
for s in to_fill:
to_fill_ids.append(orbital_id(grid, s, 0))
to_fill_ids.append(orbital_id(grid, s, 1))
to_fill_ids = to_fill_ids[0:(n_electrons - self.n_active_el)]
#print(to_fill_ids)
#print('# of terms: {}'.format(len(self.fermion_hamiltonian.terms)))
self.fermion_hamiltonian = freeze_orbitals(self.fermion_hamiltonian,
to_fill_ids)
#print('# of terms: {}'.format(len(self.fermion_hamiltonian.terms)))
# Freeze unoccupied orbitals
to_freeze_ids = range(self.n_active_orb,
n_qubits - (n_electrons - self.n_active_el))
#print(to_freeze_ids)
self.fermion_hamiltonian = freeze_orbitals(self.fermion_hamiltonian,
[], to_freeze_ids)
print('# of terms: {}'.format(len(self.fermion_hamiltonian.terms)))
# Construct qubit Hamiltonian
self.qubit_hamiltonian = jordan_wigner(self.fermion_hamiltonian)
# Initialize com;iler engine
self.compiler_engine = uccsd_trotter_engine()
