def test_berry_phase_loop(self, setup):
g = setup.g.tile(2, 0).tile(2, 1).tile(2, 2)
H = Hamiltonian(g)
bz1 = BandStructure.param_circle(H, 20, 0.01, [0, 0, 1], [1 / 3] * 3)
bz2 = BandStructure.param_circle(H,
20,
0.01, [0, 0, 1], [1 / 3] * 3,
loop=True)
assert np.allclose(berry_phase(bz1), berry_phase(bz2))
def test_berry_phase_method_fail(self):
g = Geometry([[-.6, 0, 0], [0.6, 0, 0]], Atom(1, 1.001), sc=[2, 10, 10])
g.set_nsc([3, 1, 1])
H = Hamiltonian(g)
H.construct([(0.1, 1.0, 1.5), (0, 1., 0.5)])
# Contour
k = np.linspace(0.0, 1.0, 101)
K = np.zeros([k.size, 3])
K[:, 0] = k
bz = BrillouinZone(H, K)
berry_phase(bz, method='unknown')
def test_berry_phase_zak(self):
# SSH model, topological cell
g = Geometry([[-.6, 0, 0], [0.6, 0, 0]], Atom(1, 1.001), sc=[2, 10, 10])
g.set_nsc([3, 1, 1])
H = Hamiltonian(g)
H.construct([(0.1, 1.0, 1.5), (0, 1., 0.5)])
# Contour
k = np.linspace(0.0, 1.0, 101)
K = np.zeros([k.size, 3])
K[:, 0] = k
bz = BrillouinZone(H, K)
assert np.allclose(np.abs(berry_phase(bz, sub=0, method='zak')), np.pi)
# Just to do the other branch
berry_phase(bz, method='zak')
def test_berry_phase(self, setup):
R, param = [0.1, 1.5], [1., 0.1]
g = setup.g.tile(2, 0).tile(2, 1).tile(2, 2)
H = Hamiltonian(g)
H.construct((R, param))
bz = BandStructure.param_circle(H, 20, 0.01, [0, 0, 1], [1 / 3] * 3)
berry_phase(bz)
berry_phase(bz, sub=0)
berry_phase(bz, eigvals=True, sub=0)
def test_berry_phase_fail_sc(self, setup):
g = setup.g.tile(2, 0).tile(2, 1).tile(2, 2)
H = Hamiltonian(g)
bz = BandStructure.param_circle(H.geometry.sc, 20, 0.01, [0, 0, 1],
[1 / 3] * 3)
berry_phase(bz)
