Using BC_shift on cylinder

How do I use this algorithm? What does that parameter do?
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amankumar
Posts: 29
Joined: 17 Apr 2020, 11:14

Using BC_shift on cylinder

Post by amankumar »

Dear Johannes
I was interested in to provide the different types of boundary condition in y direction for a cylinder. I want a spiral winding of chain kind of boundary condition over cylinder(may be I am after bc_shift routine but I don't know how to use it). I think usual boundary condition is just like multiple circular rings attached on cylinder. If you don't get my question let me know?
Thanks

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Johannes
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Joined: 21 Jul 2018, 12:52
Location: TU Munich

Re: Using BC_shift on cylinder

Post by Johannes »

Indeed, as far as I understand your question, you're trying to describe what the bc_shift parameter does. This one allows for a (basically) arbitrary shift when going around the cylinder; I guess you want it to be 1 or 2 in the most cases. Have you seen this section of the user-guide that I added a few month ago? Does that clarify it? Or what exactly is unclear?

If you want to "fix" the bc_shift parameter to just be -1, your system might become completely translation invariant down to a single lattice unit cell (instead of just one "ring"); in this case you can even use the tenpy.models.lattice.HelicalLattice.
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