kwant.lattice.
Monatomic
(prim_vecs, offset=None, name='', norbs=None)[source]¶A Bravais lattice with a single site in the basis.
Instances of this class provide the SiteFamily
interface.
Site tags (see SiteFamily
) are sequences of integers and
describe the lattice coordinates of a site.
Monatomic
instances are used as site families on their own or as
sublattices of Polyatomic
lattices.
Primitive vectors of the Bravais lattice.
Displacement of the lattice origin from the real space coordinates origin.
Displacement of the lattice origin from the real space coordinates origin
Methods
n_closest
(pos, n=1, group_by_length=False, rtol=1e-09)[source]¶Find n sites closest to position pos
.
An array with sites coordinates.
neighbors
(n=1, eps=1e-08)[source]¶Return n-th nearest neighbor hoppings.
Order of the hoppings to return. Note that the zeroth neighbor is the site itself or any other sites with the same position.
Tolerance relative to the length of the shortest lattice vector for when to consider lengths to be approximately equal.
The n-th nearest neighbor hoppings.
Notes
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.
normalize_tag
(tag)[source]¶Return a normalized version of the tag.
Raises TypeError or ValueError if the tag is not acceptable.
shape
(function, start)[source]¶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 Builder
instances. See example below.
A function of real space coordinates that returns a truth value: true for coordinates inside the shape, and false otherwise.
The real-space origin for the flood-fill algorithm.
Notes
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.
A Symmetry
or 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.
Examples
>>> def circle(pos):
... x, y = pos
... return x**2 + y**2 < 100
...
>>> lat = kwant.lattice.honeycomb()
>>> syst = kwant.Builder()
>>> syst[lat.shape(circle, (0, 0))] = 0
>>> syst[lat.neighbors()] = 1
vec
(int_vec)[source]¶Return the coordinates of a Bravais lattice vector in real space.
wire
(center, radius)[source]¶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 Builder
instances. See example below.
A point belonging to the axis of the cylinder.
The radius of the cylinder.
Notes
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.
Examples
>>> 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
Attributes