Search found 6 matches

by rubenv
05 Jun 2021, 12:41
Forum: HowTos and FAQ for TeNPy
Topic: [RESOLVED] Issue in purification method (normalization of temperature and/or timescales?)
Replies: 3
Views: 2973

Re: [RESOLVED] Issue in purification method (normalization of temperature and/or timescales?)

The wrong piece of code was apparently: evol1 = PurificationApplyMPO(psi,U[0],option) evol2 = PurificationApplyMPO(psi,U[1],option) evol1.run() evol2.run() The correct result is obtained with evol1 = PurificationApplyMPO(psi,U[0],option) evol1.run() evol2 = PurificationApplyMPO(psi,U[1],option) evol...
by rubenv
04 Jun 2021, 23:39
Forum: HowTos and FAQ for TeNPy
Topic: [RESOLVED] Issue in purification method (normalization of temperature and/or timescales?)
Replies: 3
Views: 2973

[RESOLVED] Issue in purification method (normalization of temperature and/or timescales?)

Hi everyone, I noticed that the finite-temperature results I obtain using the purification method do not match ED calculations; however, they do match if i change the temperature by a factor of 2 (i.e., the ED results for a temperature T seem to correspond to purification results at 'temperature' T/...
by rubenv
15 Apr 2021, 15:43
Forum: HowTos and FAQ for TeNPy
Topic: Energy gap for infinite system using segment DMRG?
Replies: 2
Views: 3262

Re: Energy gap for infinite system using segment DMRG?

Hi Johannes, Thanks, that is really helpful! I have been playing around with it today, but still can't seem to figure it out: how do I properly define the segment MPS form the original MPS? Things I have tried (where psi is the original infinite g.s. MPS obtained from iDMRG): B = [psi.get_B(i).to_nd...
by rubenv
11 Apr 2021, 18:18
Forum: HowTos and FAQ for TeNPy
Topic: Energy gap for infinite system using segment DMRG?
Replies: 2
Views: 3262

Energy gap for infinite system using segment DMRG?

Hi everyone, Currently, given a system, there are two ways of extracting an energy gap: either by doing finite DMRG (downside: there are boundary effects) or by doing periodic systems (downside: this is very costly since if naively requires the square of the original bond dimension). Ideally, there ...
by rubenv
01 Apr 2021, 19:55
Forum: HowTos and FAQ for TeNPy
Topic: Dynamical spin Structure Factor/ Excitation Spectrum of Spin Ladder
Replies: 15
Views: 9157

Re: RuntimeWarning and how to fix it

Hello! So when I calculated the dynamic spin structure factor for https://arxiv.org/abs/1701.04678, I also used iDMRG for the ground state. When calculating the overlap, I actually just used a random vector at the edge. The reasoning is: you want to take your cylinder segment wide enough anyway such...
by rubenv
03 Mar 2021, 16:35
Forum: HowTos and FAQ for TeNPy
Topic: RuntimeWarning and how to fix it
Replies: 3
Views: 2328

RuntimeWarning and how to fix it

Hi guys, I just joined the forum :) I wanted to share an issue I was having (I am using version 0.7.2). When running DMRG (or time evolution for that matter), I would sometimes get the error TeNPy/tenpy/networks/mps.py:3374: RuntimeWarning: divide by zero encountered in reciprocal S = S**form_diff H...