a = 0.24595   # [nm] unit cell length
a_cc = 0.142  # [nm] carbon-carbon distance
t =  -3.033      # [eV] nearest neighbour hopping


def monolayer_graphene():
    # create a lattice with 2 primitive vectors
    lat = pb.Lattice(
        a1=[a/2, a/2 * sqrt(3)],
        a2=[a/2, -a/2 * sqrt(3)]
    )

    lat.add_sublattices(
        # name and position
        ('A', [0, -a_cc/2]),
        ('B', [0,  a_cc/2])
    )

    lat.add_hoppings(
        # inside the main cell
        ([0,  0], 'A', 'B', t),
        # between neighboring cells
        ([0, 1], 'A', 'B', t),
        ([-1, 0], 'A', 'B', t),
             
       
    )

    return lat
	
lattice = monolayer_graphene()
model = pb.Model(monolayer_graphene(),pb.translational_symmetry())

model.plot(site={'radius': 0.02, 'cmap': ['blue', 'red']},\
             hopping={'width': 1, 'cmap': ['grey']})

model.lattice.plot_vectors(position=[0,0])

# For the brillouin zone 
model.lattice.plot_brillouin_zone()