Dear ALPS Member,
I am trying to run ALPS DMRG to calculate gap for a spin system on 3-chain lattice. My energy eigenvalue is degenerate and I am trying to divide the system to different sector using the constraint. I want to set an eigenvalue of one operator to have a specific value.
My problem is the operator which divide my Hilbert space to different sector is not local and depends on several site. I am wondering if I can do that with constraint.
Should I define a new quantum number other than Sz?
Thank you for your help,
Best,
Ali
Hi,
constraints are unfortunately just sums of local operators. You might be able to work around this be defining bigger unit cells. We might be able to help if you tell us what exactly your constraint is.
Matthias Troyer
On Mar 6, 2013, at 11:28 PM, Ali Beyramzadeh Moghadam ali.beyramzadehmoghadam@email.ucr.edu wrote:
Dear ALPS Member,
I am trying to run ALPS DMRG to calculate gap for a spin system on 3-chain lattice. My energy eigenvalue is degenerate and I am trying to divide the system to different sector using the constraint. I want to set an eigenvalue of one operator to have a specific value. My problem is the operator which divide my Hilbert space to different sector is not local and depends on several site. I am wondering if I can do that with constraint. Should I define a new quantum number other than Sz?
Thank you for your help, Best, Ali
If you are interested, I was working in a patch to implement parity-type constraints and I have now a beta release which (at least) works fine for the eigensolvers.
Mauricio
2013/3/7 Matthias Troyer troyer@phys.ethz.ch
Hi,
constraints are unfortunately just sums of local operators. You might be able to work around this be defining bigger unit cells. We might be able to help if you tell us what exactly your constraint is.
Matthias Troyer
On Mar 6, 2013, at 11:28 PM, Ali Beyramzadeh Moghadam < ali.beyramzadehmoghadam@email.ucr.edu> wrote:
Dear ALPS Member,
I am trying to run ALPS DMRG to calculate gap for a spin system on 3-chain lattice. My energy eigenvalue is degenerate and I am trying to divide the system to different sector using the constraint. I want to set an eigenvalue of one operator to have a specific value. My problem is the operator which divide my Hilbert space to different sector is not local and depends on several site. I am wondering if I can do that with constraint. Should I define a new quantum number other than Sz?
Thank you for your help, Best, Ali
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