Geometry creation – part 2

Many geometries are intrinsically enabled via the sisl.geom submodule.

Here we list the currently default geometries:

honeycomb (graphene unit-cell):

hBN = geom.honeycomb(1.5, [Atom('B'), Atom('N')])

graphene (equivalent to honeycomb with Carbon atoms):
```
graphene = geom.graphene(1.42)
```

Simple-, body- and face-centered cubic as well as HCP All have the same interface:

sc = geom.sc(2.5)
bcc = geom.bcc(2.5)
fcc = geom.fcc(2.5)
hcp = geom.hcp(2.5)

Nanotubes with different chirality:

ntb = geom.nanotube(1.54, chirality=(n, m))