TeNPy Forum

Thank you for the response. I have another difficulty in this part, I saw source code of get_rho_segment , where sorting is done for segment sites. So If I am evaluating \rho_{ij} , where index i>j , and I will transform it into a 4\times 4 matrix. So, now I am interested in \rho_{ji} density matrix...

Can I see my two site reduced density matrix in this below format, where I can get to know about each elements of the matrix. \begin{matrix} c_{\uparrow_i\uparrow_j\uparrow_i\uparrow_j} & c_{\uparrow_i\uparrow_j\uparrow_i\downarrow_j} & c_{\uparrow_i\uparrow_j\downarrow_i\uparrow_j} &c_{...

1.) Is there a way to get full \rho_i in matrix form or do I have to calculate each matrix element separately as you suggested above. 2.) Also can I calculate this quantity \langle \Psi | \downarrow_i\rangle , as one way I think of by taking square root of corresponding density matrix element, but t...

Hi I want to know, is there a way to calculate probability to find particle at any site i in up (or down) state? Like if I have a state |\Psi> in MPS form and I want to evaluate this quantity <\Psi|down_i> , where |down_i> is linear combination of all simple basis state where at site i it is down an...

Yes while copying code here, I missed that term, which I have updated now. But still I did not understood this distinct behaviour of ground state with or without parity.
Also, how to implement total Sz conserve symmetry here?

Yes I am considering Ferromagnetic Heisenberg model on hexagonal lattice. Here is my code from tenpy.algorithms import dmrg import numpy as np from mps import MPS from tenpy.models.lattice import Lattice, get_order, _parse_sites,Honeycomb from tenpy.networks.site import SpinHalfSite from tenpy.model...

Thanks That is fine, when parity is conserved, state is in all up state plus down state, which is confirmed by zero expectation vale of Sz on a site. And in other case, when I turn off parity, I get state to be in all up configuration, confirmed by "one" expectation value of Sz on a site. ...

Hi
If you need more details, or did not understood my question, please let me know.
Thanks

Thanks it works fine, but only for small bond dimension. I have another conceptual question in dmrg, I was simulating ferromagnetic heisenberg model using tenpy, and evaluated ground state entanglement entropy for some subsystem. I got Log(2) as answer, as this is obvious ground state preserves spin...

Hi I wanted to evaluate entanglement entropy for a segment of sites with function entanglement_entropy_segment(). But this can not take more than or equal 12 sites as memory issue. Can I exploit lattice symmetries like translation one using tenpy package, and can extend my segment size to more than ...

Thank you for the update to allow torus-boundary conditions. And as you pointed I implemented it on Toric Code model and bond dimension is squared as compared to infinite cylinder. 1.) But now I am getting back to my old thread question. I am trying to evaluate entanglement for a system size L_x=L_y...

I am sorry for posting question in "Papers using TeNPy", I don't remember how did I posted it there. I tried to use Irregular Lattice for Toric Code model by removing those sites which do not belong to any Plaquette of the original square lattice. I am getting an unusual error. Can you hel...

In the new released you updated the Irregular lattice site where one can remove some sites. I read the documentation but did not understood how to specify the sites which one wants to remove. I considered Toric code model(L_x=3,L_y=3) and wanted to remove all sites(18,19,20,21,22,23) which are not s...

I understand that, I deliberately tried to change the lattice basis vector and order in Honeycomb lattice. 1.) How to change the model such that it supports toroidal boundary condition, as you suggested in earlier post. Can you guide me for this your famous toric code example. 2.) I tried to impleme...

Thank you for such a beautiful explanation, 1.) I understand by changing the winding direction, bond dimensions changes depending on the interaction. As you said one can try different geometry(changing the winding) and try to see MPS entropy, Is there another possible geometry possible for square la...

Can you explain a bit more your second point. Of course entanglement entropy is basis dependent, if you write the Hamiltonian in the basis of exact eigenstate of model, then in that basis ground state would be pure state. But I do not understand how the bond dimension is reduced in Dual Square latti...

Thank You for the clarification, 1.)Does tenpy also implement toroidal boundary condition ? 2.) I have another question not related to the thread, Suppose I have a model whose ground state is highly entangled, and it requires huge number of chi_max. So can you suggest me some way reduce chi_max, or ...

Thank you for your clarification. But I am concerned about one point, that whether these two operations of entanglement entropy gives the same answer or not for a same subsystem. So I did a check for a given example of Toric Code Model. Here I took Lx=2,Ly=3 and evaluated ent. entropy for same subsy...

Hey I wanted to evaluate entanglement entropy for a subsystem given by sites in segment parameter in entanglement_entropy_segment function. It should give entropy of this subsystem meaning just one numeric number. But in return I am getting array of entropies. I completely don't understand what each...