Beispiel #1
0
def test_higher_dim():
    # Test 0D finite system
    lat = kwant.lattice.cubic(norbs=1)
    syst = kwant.Builder()
    syst[lat(0, 0, 0)] = 1
    syst[lat(1, 1, 0)] = 1
    syst[lat(0, 1, 1)] = 1
    syst[lat(1, 0, -1)] = 1
    syst[lat(0, 0, 0), lat(1, 1, 0)] = -1
    syst[lat(0, 0, 0), lat(0, 1, 1)] = -1
    syst[lat(0, 0, 0), lat(1, 0, -1)] = -1

    H = builder_to_model(syst)
    sg, cs = symmetries(H, prettify=True)
    assert len(sg) == 2
    assert len(cs) == 5

    # Test triangular lattice system embedded in 3D
    sym = TranslationalSymmetry([1, 1, 0], [0, 1, 1])
    lat = kwant.lattice.cubic(norbs=1)
    syst = kwant.Builder(symmetry=sym)
    syst[lat(0, 0, 0)] = 1
    syst[lat(0, 0, 0), lat(1, 1, 0)] = -1
    syst[lat(0, 0, 0), lat(0, 1, 1)] = -1
    syst[lat(0, 0, 0), lat(1, 0, -1)] = -1

    H = builder_to_model(syst)
    sg, cs = symmetries(H, hexagonal(sympy_R=False), prettify=True)
    assert len(sg) == 24
    assert len(cs) == 0
Beispiel #2
0
def test_honeycomb():
    lat = kwant.lattice.honeycomb(norbs=1)

    # Test simple honeycomb model with constant terms
    # Add discrete symmetries to the kwant builder as well, to check that they are
    # returned as well.
    syst = kwant.Builder(symmetry=TranslationalSymmetry(*lat.prim_vecs))
    syst[lat.a(0, 0)] = 1
    syst[lat.b(0, 0)] = 1
    syst[lat.neighbors(1)] = -1

    H = builder_to_model(syst)
    sg, cs = symmetries(H, hexagonal(sympy_R=False), prettify=True)
    assert len(sg) == 24
    assert len(cs) == 0

    # Test simple honeycomb model with value functions
    syst = kwant.Builder(symmetry=TranslationalSymmetry(*lat.prim_vecs))
    syst[lat.a(0, 0)] = lambda site, ma: ma
    syst[lat.b(0, 0)] = lambda site, mb: mb
    syst[lat.neighbors(1)] = lambda site1, site2, t: t

    H = builder_to_model(syst)
    sg, cs = symmetries(H, hexagonal(sympy_R=False), prettify=True)
    assert len(sg) == 12
    assert len(cs) == 0