Hi Johnny,

Just to add something, if your lattice is simple enough and all the
atoms in the bulk have the same number of neighbors, then you can
figure out which atoms are on the edge for example like this: [i for i
in range(len(syst.graph.num_nodes)) if
len(syst.graph.out_neighbors(i)) < 3]. Note: 3 in the expression is
the number of neighbors in the bulk.

Cheers,
Anton

On Thu, Apr 14, 2016 at 12:16 PM, Joseph Weston
<joseph.weston08@gmail.com> wrote:
> Hi,
>
> you can get the indices of all the sites in the finialized system by using
> the `sites`
> property of finalized systems. After that , it's just a case of writing a
> function that
> can filter this list based on whether a site is on the `edge` or not. You
> would have
> to define this filtering yourself. For graphene I would imagine that such a
> filter would
> involve querying the number of neighbours of a particular site.
>
> Happy Kwanting,
>
> Joe