Hi Chong Wang,

For an example use of wraparound please see this notebook: https://github.com/topocm/topocm_content/blob/master/w6_3dti/bhz.ipynb

Here we have a 2D slab connected to a 3D infinite system, the relevant code is in make_scatter_sys.


Bas Nijholt

On Wed, 11 May 2016 at 16:47 Chong Wang <Chong Wang > wrote:

Thanks for your reply.

In the kwant paper, I think fig 7 indicates ~1000GB memory is needed for such a system. Also, I only replicated my unit cell twice in the y direction. It seems that I need to figure out some tricks to work around this.


From: Joseph Weston <joseph.weston08@gmail.com>
Sent: Wednesday, May 11, 2016 9:53 PM
To: Chong Wang
Cc: kwant-discuss@kwant-project.org
Subject: Re: [Kwant] scatter without a center area


`lead.cell_hamiltonian()` gives 32000. The thickness of my slab is 50. Is this something not possible to calculate?

Ok, now it certainly makes sense that the memory blows up; the kwant paper[1] indicates
that the memory requirement for solving this sort of size should be ~ 100GB.

Anton reminded me of a workaround written by Christoph for dealing with periodic
systems. You can find the code over here[2] (if you don't want to download it
using git you can get the raw python module here[3]). You should be able to
use this instead of replicating your unit cell in the y direction, which should drastically
reduce your memory/runtime requirements.



[1]: http://downloads.kwant-project.org/doc/kwant-paper.pdf
Kwant: a software package for quantum transport Christoph W. Groth,1 Michael Wimmer,2 Anton R. Akhmerov,2,3 and Xavier Waintal1 1CEA-INAC/UJF Grenoble 1, SPSMS UMR-E ...

[2]: https://gitlab.kwant-project.org/cwg/wraparound
[3]: https://gitlab.kwant-project.org/cwg/wraparound/raw/master/wraparound.py