コード例 #1
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def test_attach():
    """Attach 2 leads to a square lattice system"""
    w, h = 2, 3
    model = square_model(w, h)
    model.attach_lead(-1, pb.line([0, -h / 2], [0, h / 2]))
    model.attach_lead(+1, pb.line([0, -h / 2], [0, h / 2]))
    assert len(model.leads) == 2
    assert np.all(model.leads[0].indices == [0, 2, 4])
    assert np.all(model.leads[1].indices == [1, 3, 5])

    # Linear hopping grows from lead 0 to system to lead 1
    model.add(linear_hopping())
    assert model.leads[0].h1.data.max() < model.hamiltonian.data.min()
    assert model.hamiltonian.data.max() < model.leads[1].h1.data.min()

    # With the linear hopping modifier, the h1 hoppings should be equal to the
    # x position between the lead and main system
    x_mid_0 = (model.system.x.min() + model.leads[0].system.x.max()) / 2
    assert np.allclose(model.leads[0].h1.data, x_mid_0)
    x_mid_1 = (model.system.x.max() + model.leads[1].system.x.min()) / 2
    assert np.allclose(model.leads[1].h1.data, x_mid_1)

    # Linear onsite potential grows from lead 0 to system to lead 1
    model.add(linear_onsite())
    assert model.leads[0].h0.diagonal().max() < model.hamiltonian.diagonal(
    ).min()
    assert model.hamiltonian.diagonal().max() < model.leads[1].h0.diagonal(
    ).min()
コード例 #2
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ファイル: test_shape.py プロジェクト: suthzx/pybinding
def test_line():
    """1D shape with 1D lattice"""
    model = pb.Model(examples.chain_lattice(a=1), pb.line(0, 4.5))
    assert model.system.num_sites == 4

    model = pb.Model(examples.chain_lattice(a=1), pb.line([0, -0.5], [5, 0.5]))
    assert model.system.num_sites == 6
コード例 #3
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 def make_model(v0=0):
     model = pb.Model(
         graphene.monolayer().with_min_neighbors(1),
         pb.rectangle(length, width),
         potential_barrier(v0),
     )
     model.attach_lead(
         -1, pb.line([-length / 2, -width / 2], [-length / 2, width / 2]))
     model.attach_lead(
         +1, pb.line([length / 2, -width / 2], [length / 2, width / 2]))
     return model
コード例 #4
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def test_api(ring_model):
    with pytest.raises(RuntimeError) as excinfo:
        ring_model.attach_lead(0, pb.line(0, 0))
    assert "Lead direction must be one of" in str(excinfo.value)

    for direction in [3, -3]:
        with pytest.raises(RuntimeError) as excinfo:
            ring_model.attach_lead(direction, pb.line(0, 0))
        assert "not valid for a 2D lattice" in str(excinfo.value)

    with pytest.raises(RuntimeError) as excinfo:
        pb.Model(examples.chain_lattice()).attach_lead(2, pb.line(0, 0))
    assert "Attaching leads to 1D lattices is not supported" in str(
        excinfo.value)
コード例 #5
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ファイル: test_kwant.py プロジェクト: zhuchangyan/pybinding
    def pb_model(v=0, length=2, width=10):
        def square_lattice(d, t):
            lat = pb.Lattice(a1=[d, 0], a2=[0, d])
            lat.add_sublattices(("A", [0, 0], 4 * t))
            lat.add_hoppings(([0, 1], "A", "A", -t), ([1, 0], "A", "A", -t))
            return lat

        @pb.onsite_energy_modifier
        def potential_well(energy, x):
            energy[np.logical_and(x >= 0, x <= 1)] -= v
            return energy

        model = pb.Model(square_lattice(d=1, t=1), pb.rectangle(length, width),
                         potential_well)
        model.attach_lead(-1, pb.line([0, -width / 2 - 0.1], [0, width / 2]))
        model.attach_lead(+1, pb.line([0, -width / 2 - 0.1], [0, width / 2]))
        return model
コード例 #6
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def test_empty(ring_model):
    with pytest.raises(RuntimeError) as excinfo:
        ring_model.attach_lead(2, pb.line(0, 0))
        assert ring_model.system
    assert "no sites in lead junction" in str(excinfo.value)
コード例 #7
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def test_complete_miss(ring_model):
    with pytest.raises(RuntimeError) as excinfo:
        ring_model.attach_lead(2, pb.line([4, -5], [5, -5]))
        assert ring_model.system
    assert "completely misses main structure" in str(excinfo.value)
コード例 #8
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ファイル: test_kwant.py プロジェクト: oroszl/pybinding
 def pb_model(v=0, length=2, width=10):
     model = pb.Model(square_lattice(d=1, t=1),
                      pb.rectangle(x=length, y=width), potential_well(v))
     model.attach_lead(-1, pb.line([0, -width / 2 - 0.1], [0, width / 2]))
     model.attach_lead(+1, pb.line([0, -width / 2 - 0.1], [0, width / 2]))
     return model
コード例 #9
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ファイル: line.py プロジェクト: zx-sdu/pybinding
import matplotlib.pyplot as plt

pb.pltutils.use_style()


def simple_chain_lattice(a=1, t=-1):
    """Very simple 1D lattice"""
    lat = pb.Lattice(a)
    lat.add_one_sublattice('A', [0, 0])
    lat.add_one_hopping(1, 'A', 'A', t)
    return lat


model = pb.Model(
    simple_chain_lattice(),
    pb.line(-3.5, 3.5)  # line start/end in nanometers
)
model.plot()
plt.show()


def trestle(a=0.2, t1=0.8 + 0.6j, t2=2):
    """A more complicated 1D lattice with 2 sublattices"""
    lat = pb.Lattice(1.3 * a)
    lat.add_sublattices(('A', [0, 0], 0), ('B', [a / 2, a], 0))
    lat.add_hoppings((0, 'A', 'B', t1), (1, 'A', 'B', t1), (1, 'A', 'A', t2),
                     (1, 'B', 'B', t2))
    lat.min_neighbors = 2
    return lat