def test_sz_operator(self):
op = sz_operator(2)
expected = (FermionOperator(((0, 1), (0, 0)), 0.5) - FermionOperator(
((1, 1), (1, 0)), 0.5) + FermionOperator(
((2, 1), (2, 0)), 0.5) - FermionOperator(
((3, 1), (3, 0)), 0.5))
self.assertTrue(op == expected)
def test_relations(self):
n_spatial_orbitals = 2
s_plus = s_plus_operator(n_spatial_orbitals)
s_minus = s_minus_operator(n_spatial_orbitals)
sx = sx_operator(n_spatial_orbitals)
sy = sy_operator(n_spatial_orbitals)
sz = sz_operator(n_spatial_orbitals)
s_squared = s_squared_operator(n_spatial_orbitals)
identity = FermionOperator(())
self.assertEqual(normal_ordered(sx),
normal_ordered(.5 * (s_plus + s_minus)))
self.assertEqual(normal_ordered(sy),
normal_ordered((.5 / 1.j) * (s_plus - s_minus)))
self.assertEqual(normal_ordered(s_squared),
normal_ordered(sx**2 + sy**2 + sz**2))
self.assertEqual(
normal_ordered(s_squared),
normal_ordered(s_plus * s_minus + sz * (sz - identity)))
self.assertEqual(normal_ordered(commutator(s_plus, s_minus)),
normal_ordered(2 * sz))
self.assertEqual(normal_ordered(commutator(sx, sy)),
normal_ordered(1.j * sz))
def test_invalid_input(self):
with self.assertRaises(TypeError):
s_minus_operator('a')
with self.assertRaises(TypeError):
s_plus_operator('a')
with self.assertRaises(TypeError):
sx_operator('a')
with self.assertRaises(TypeError):
sy_operator('a')
with self.assertRaises(TypeError):
sz_operator('a')
with self.assertRaises(TypeError):
s_squared_operator('a')