Search found 10 matches

by nsherman
14 Jul 2022, 00:53
Forum: HowTos and FAQ for TeNPy
Topic: Different Energy measures giving mixed results
Replies: 1
Views: 1425

Different Energy measures giving mixed results

Hi, I'm looking at the time-evolution of a product state under a time-dependent Hamiltonian using iTEBD. For certain simulation parameters, it's the case that when I measure the bond-energy, using M.bond_energies() for a model M, that energy is different for the two bonds. This is an issue in my res...
by nsherman
20 Apr 2022, 22:22
Forum: HowTos and FAQ for TeNPy
Topic: Charge Info for Z3 symmetry in 3-state Potts Model
Replies: 3
Views: 2863

Charge Info for Z3 symmetry in 3-state Potts Model

Hi, I'm trying to implement the 3-state Potts Model, with Hamiltonian H = \sum_i \Omega^{\dagger}_i\Omega_{i+1} + \Omega_i\Omega^{\dagger}_{i+1} + \sum_i [\Gamma_i^{(1)} + \Gamma_i^{(2)}] with \Omega_i = diag(1, e^{i2\pi/3}, e^{-i2\pi/3}) And \Gamma_i^{(1)} is a cyclic permutation of the 3 basis sta...
by nsherman
18 Aug 2021, 22:25
Forum: Algorithms
Topic: iTDVP and canonical forms
Replies: 2
Views: 7405

iTDVP and canonical forms

I'm working on developing an iTDVP algorithm using TeNPy. I'm able to recycle most of the aspects from the finite TDVP code, but there are some issues when trying to insert the updated tensors to for an updated MPS. Essentially, we have a 1-site and 0-site effective Hamiltonian that we use to update...
by nsherman
16 Jun 2021, 23:42
Forum: HowTos and FAQ for TeNPy
Topic: Singular Values as np_conserved
Replies: 1
Views: 1637

Singular Values as np_conserved

I'm trying to implement the iTDVP algorithm following https://scipost.org/SciPostPhysLectNotes.7/pdf In doing this, I need to update both the center site tensor using the '1-site' Hamiltonian, as well as the center site singular values using the '0-site' Hamiltonian. In order to do this, I'd like to...
by nsherman
09 Jun 2021, 19:43
Forum: Algorithms
Topic: Question about iTDVP
Replies: 1
Views: 6421

Question about iTDVP

I'm trying to implement the infinite TDVP algorithm based on these notes https://arxiv.org/abs/1810.07006 It seems like these are the main steps: 1) Find the left and right environments 2) Use these to create effective Hamiltonians 0, and 1 site. 3) Integrate the TDVP equations to update the MPS ten...
by nsherman
04 May 2021, 00:55
Forum: HowTos and FAQ for TeNPy
Topic: Dynamics with Segment Boundary Conditions
Replies: 0
Views: 31671

Dynamics with Segment Boundary Conditions

I'm looking to study time-dependent two-point correlation functions following the prescription laid out in https://arxiv.org/abs/1207.0652 It seems like 'segment' boundary condition is what I'm looking for, but I'm confused on how to utilize this. What I want to do is use iDMRG to find the ground st...
by nsherman
28 Apr 2021, 00:48
Forum: HowTos and FAQ for TeNPy
Topic: Correlation function with infinite boundary conditions
Replies: 4
Views: 3038

Re: Correlation function with infinite boundary conditions

Great, I was thinking it's what I'm looking for. I have another possibly naive question. How do I actually use "segment"? I want to use infinite boundary conditions to find the ground state with DMRG, but then I want to transition to segment for the time evolution. So how would I go about ...
by nsherman
27 Apr 2021, 02:26
Forum: HowTos and FAQ for TeNPy
Topic: Correlation function with infinite boundary conditions
Replies: 4
Views: 3038

Re: Correlation function with infinite boundary conditions

I guess I forgot to mention explicitly that I want to study dynamics, so <Sz(x,t)Sz(0,0)> say. It seems like in order to time evolve Sz|psi>, I need to strictly work at finite system size, since the state is no longer translationally invariant. However, to eliminate boundary effects, one can use edg...
by nsherman
21 Apr 2021, 00:30
Forum: HowTos and FAQ for TeNPy
Topic: Correlation function with infinite boundary conditions
Replies: 4
Views: 3038

Correlation function with infinite boundary conditions

Hi, I'm new to TenPy, and I'm looking to compute correlation functions using infinite boundary conditions, based on this paper https://arxiv.org/abs/1207.0652 What I'm wondering is if this functionality is already baseline in TenPy? I'm thinking the 'segment' boundary condition might be what I'm loo...