How to handle with 1-D Bose-Fermi mixture by using DMRG with iTensor

+2 votes
asked Feb 8 by JunjieChen (340 points)
retagged Feb 8 by JunjieChen

Hello, I'm currently considering a 1-D Bose-Fermi spinor mixture system, in which fermion is spin-1/2 and boson is spin-1 and soft(not hard core).

I have noticed this nice answer: http://itensor.org/support/118/constructing-sites-chain-alternating-bosonic-degrees-freedom which consider a similar question. Is this strategy also applicable for my problems ? That is, I just need to write my own SiteSet file to define the lattice model I consider. Nothing needs to be changed to AutoMPO and MPO or DMRG function itself when I construct my Hamiltonian and do the calculation.

By the way, is there any other way to construct this 1-D B-F mixture ? For example, we may treat this 1-D lattice as a connected 1-D ladder with one of this being spin-1 and other being spin-1/2, just as the example given in the tutorial of iTensor.

Thanks ! PS: iTensor is really a fascinating MPS library with simple data structure.

1 Answer

+1 vote
answered Feb 9 by miles (12,650 points)

Thanks for the kind words. The good news is that all you need is a custom site set and then all of the other parts of the code (such as AutoMPO, MPO, DMRG) should just automatically work. I recently made a site set for a student who is doing a two-leg ladder setup like you suggested where each leg has a different type of quantum number. If you email me I can send you the source code for this site set for you to use as an example.

To deal with fermions specifically, things might get a bit tricky with AutoMPO. We'd probably have to talk about how to deal with it best. But I think it could work ok. Basically you'd have to define a fermion string operator called "F" for both fermion and boson sites, and just define it to be a trivial identity operator for the fermion sites.

Ultimately this would be a good type of SiteSet to add to ITensor.

Miles

Welcome to ITensor Support Q&A, where you can ask questions and receive answers from other members of the community.

Formatting Tips:
  • To format code, indent by four spaces
  • To format inline LaTeX, surround it by @@ on both sides
  • To format LaTeX on its own line, surround it by $$ above and below
If you cannot register due to firewall issues (e.g. you cannot see the capcha box) please email Miles Stoudenmire to ask for an account.

To report ITensor bugs, please use the issue tracker.
...