def test_random_mps_invalid_dimensions_raises_error(backend_dtype_values):
with pytest.raises(ValueError):
FiniteMPS.random(d=[3, 4],
D=[2, 3],
dtype=backend_dtype_values[1],
backend=backend_dtype_values[0])
with pytest.raises(ValueError):
FiniteMPS.random(d=[3, 4, 4, 2],
D=[2, 3],
dtype=backend_dtype_values[1],
backend=backend_dtype_values[0])
def test_random_mps(backend_dtype_values):
mps = FiniteMPS.random(d=[3, 4, 5],
D=[2, 3],
dtype=backend_dtype_values[1],
backend=backend_dtype_values[0])
assert len(mps) == 3
assert mps.physical_dimensions == [3, 4, 5]
assert mps.bond_dimensions == [1, 2, 3, 1]
def test_identity_mpo():
N = 10
psi = FiniteMPS.random([2 for i in range(10)], [4 for i in range(9)],
dtype=np.float64)
Id = identity_mpo(N)
lh = LocalHam(Id, psi, "numpy")
# test shifting right
for b in range(len(psi) - 1):
lh.position(b)
assert np.isclose(lh.energy(), 1, atol=1e-10)
# test shifting back left
for b in range(len(psi) - 2, -1, -1):
lh.position(b)
assert np.isclose(lh.energy(), 1, atol=1e-10)
def test_finiteFreeFermions2d(N1, N2, D):
def adjacency(N1, N2):
neighbors = {}
mat = np.arange(N1 * N2).reshape(N1, N2)
for n in range(N1 * N2):
x, y = np.divmod(n, N2)
if n not in neighbors:
neighbors[n] = []
if y < N2 - 1:
neighbors[n].append(mat[x, y + 1])
if x > 0:
neighbors[n].append(mat[x - 1, y])
return neighbors
adj = adjacency(N1, N2)
tij = np.zeros((N1 * N2, N1 * N2))
t = -1
v = -1
for n, d in adj.items():
for ind in d:
tij[n, ind] += t
tij[ind, n] += t
tij += np.diag(np.ones(N1 * N2) * v)
eta, _ = np.linalg.eigh(tij)
expected = min(np.cumsum(eta))
t1 = t
t2 = t
dtype = np.float64
mpo = FiniteFreeFermion2D(t1, t2, v, N1, N2, dtype)
mps = FiniteMPS.random([2] * N1 * N2, [D] * (N1 * N2 - 1),
dtype=np.float64)
dmrg = FiniteDMRG(mps, mpo)
actual = dmrg.run_one_site()
np.testing.assert_allclose(actual, expected)