Polyatomic(prim_vecs, basis, name='')¶
A Bravais lattice with an arbitrary number of sites in the basis.
prim_vecs : 2d array-like of floats
basis : 2d array-like of floats
name : string or sequence of strings
Return n-th nearest neighbor hoppings.
n : integer
eps : float
hoppings : list of kwant.builder.HopplingKind objects
The hoppings are ordered lexicographically according to sublattice from which they originate, sublattice on which they end, and their lattice coordinates. Out of the two equivalent hoppings (a hopping and its reverse) only the lexicographically larger one is returned.
Return a key for all the lattice sites inside a given shape.
The object returned by this method is primarily meant to be used as a
key for indexing
kwant.Builder instances. See example below.
function : callable
start : 1d array-like
shape_sites : function
When the function returned by this method is called, a flood-fill algorithm finds and yields all the lattice sites inside the specified shape starting from the specified position.
Builder may be passed as
sole argument when calling the function returned by this method. This
will restrict the flood-fill to the fundamental domain of the symmetry
(or the builder’s symmetry). Note that unless the shape function has
that symmetry itself, the result may be unexpected.
>>> def circle(pos): ... x, y = pos ... return x**2 + y**2 < 100 ... >>> lat = kwant.lattice.honeycomb() >>> sys = kwant.Builder() >>> sys[lat.shape(circle, (0, 0))] = 0 >>> sys[lat.neighbors()] = 1
Return the coordinates of a Bravais lattice vector in real space.
|Parameters:||vec : integer vector|
|Returns:||output : real vector|
Return a key for all the lattice sites inside an infinite cylinder.
This method makes it easy to define cylindrical (2d: rectangular) leads
that point in any direction. The object returned by this method is
primarily meant to be used as a key for indexing
instances. See example below.
center : 1d array-like of floats
radius : float
The function returned by this method is to be called with a
TranslationalSymmetry instance (or a
Builder instance whose symmetry is used then) as sole
argument. All the lattice sites (in the fundamental domain of the
symmetry) inside the specified infinite cylinder are yielded. The
direction of the cylinder is determined by the symmetry.
>>> lat = kwant.lattice.honeycomb() >>> sym = kwant.TranslationalSymmetry(lat.a.vec((-2, 1))) >>> lead = kwant.Builder(sym) >>> lead[lat.wire((0, -5), 5)] = 0 >>> lead[lat.neighbors()] = 1
(sequence of vectors) Primitive vectors
prim_vecs[i]` is the i-th primitive basis vector of the lattice displacement of the lattice origin from the real space coordinates origin.