Search found 13 matches

by Qottmann
17 Jun 2020, 12:59
Forum: HowTos and FAQ for TeNPy
Topic: Superposition of MPS with different total charge
Replies: 4
Views: 310

Re: Superposition of MPS with different total charge

Thanks for the answer, that helped a lot (as always!) Concerning your question why one would want to do that: I'm trying to compare ground states for a certain filling via chemical potential and via symmetry. In the case of fixing the symmetry we obtained a funny pattern in the entanglement spectrum...
by Qottmann
16 Jun 2020, 14:30
Forum: HowTos and FAQ for TeNPy
Topic: Superposition of MPS with different total charge
Replies: 4
Views: 310

Superposition of MPS with different total charge

Hi, is there a way to use MPS.add(other,alpha,beta) for two MPS that have different total charge? I guess a brute force workaround would be to obtain the full matrices via get_B() (with all unnecessary 0s) and then create a new "empty" state and set_B(). Is there a direct way? I actually have no ide...
by Qottmann
13 May 2020, 08:06
Forum: HowTos and FAQ for TeNPy
Topic: Square of MPO
Replies: 3
Views: 1044

Re: Square of MPO

Thanks for the quick reply and update!

I actually need it for infinite systems, do you (or anybody else) know of another way to check "how good an eigenstate" the result is other than the variance?
by Qottmann
11 May 2020, 10:43
Forum: HowTos and FAQ for TeNPy
Topic: Square of MPO
Replies: 3
Views: 1044

Square of MPO

Hello, does anybody know an _easy_ way to compute the square of a MPO/model? I want to compute something like (\Delta H)^2 = <H>^2 - <H^2> to check how good an Eigenstate my result is. Defining a new model that is the square of the Hamiltonian by hand seems rather cumbersome (and doesnt lead to a ni...
by Qottmann
14 Oct 2019, 10:19
Forum: HowTos and FAQ for TeNPy
Topic: finite open, finite periodic and infinite periodic chains
Replies: 1
Views: 1023

finite open, finite periodic and infinite periodic chains

Hello, is there a way to have a finite periodic chain (so a ring) for the BoseHubbard model? As far as I understand setting bc_MPS to "finite" gives a finite chain with open boundary conditions and "infinite" is basically performing iDMRG - or am I already getting this part wrong? Thanks in advance!...
by Qottmann
13 Jun 2019, 17:52
Forum: HowTos and FAQ for TeNPy
Topic: norm_tol parameter for DMRG
Replies: 2
Views: 649

Re: norm_tol parameter for DMRG

Any answer to this?
by Qottmann
08 May 2019, 14:39
Forum: HowTos and FAQ for TeNPy
Topic: Brute force parallel execution / multiprocessing
Replies: 1
Views: 838

Brute force parallel execution / multiprocessing

Hello again, Disclaimer: I am far from a computer scientist and probably mix and use wrong terminology :D Also, I am not talking about going deep into the implementation like here https://tenpy.johannes-hauschild.de/viewtopic.php?t=4 I have to calculate many independent ground states for different p...
by Qottmann
03 May 2019, 13:47
Forum: HowTos and FAQ for TeNPy
Topic: How to get the data of NPC arrays
Replies: 1
Views: 449

How to get the data of NPC arrays

Hello again, I sometimes want to look at the actual data of the tensors in an MPS or MPO network, but I am a bit puzzled by the ._data attribute. For example, I want the W tensor of a Bose Hubbard model w/o conservation. I create the model model_params = dict( filling = 1., n_max = 4, t = 1, U = 1, ...
by Qottmann
29 Apr 2019, 15:03
Forum: HowTos and FAQ for TeNPy
Topic: Cython compilation error
Replies: 5
Views: 1297

Re: Cython compilation error

I did not specifically install this compiler, no. I asked our admin to check if gcc is up to date (which it was) but he also updated a bunch of other things and now it is working. I dont know what exactly was the problem (so for future references this thread might be not very helpful) but at least i...
by Qottmann
29 Apr 2019, 12:24
Forum: HowTos and FAQ for TeNPy
Topic: Cython compilation error
Replies: 5
Views: 1297

Re: Cython compilation error

Hello Johannes, thanks again for the answer! On my personal computer on Ubuntu 18 it works fine, the problem here is on a Ubuntu 16 server. When I try to compile your minimal example I get a similar error: (tenpy) kkottmann@pcl1016:~$ cythonize -bi a.pyx Compiling /home/kkottmann/a.pyx because it ch...