January 2018 - Comp-phys-alps-users

susceptibility problem
by Stanislaw Galeski 12 Jan '18

12 Jan '18

Hi everyone, Im new to ALPS so i apologize if my question is silly, however i did not manage to find an answer neither in the mailing list nor on the wiki. I am trying to calculate the magnetic susceptibility of a spin 1/2 ladder in a magnetic field above Hc1. Unfortunately the result i got is very puzzling: The calculated uniform susceptibility differs a lot from the susceptibility calculated as dM/dH. I was using the dirloop_sse algorithm on a 400 site ladder. Is there an easy explanation of this issue? Best, Stanislaw

1 0

The meaning of the 'TruncatedWeight' in ALPS MPS simulation
by Rongyang Sun 11 Jan '18

11 Jan '18

Dear ALPS users, The ALPS MPS code can print 'TruncatedWeight' to estimate the error of the simulation. I have a question: What is the meaning of this quantity and the relation with the truncation error in traditional DMRG simulation? For Fig. 5 in Computer Physics Communications, 185(12):3430 – 3440, 2014., the quantity may be summed as the final truncation error after a sweep. Thanks a lot! Best regards, Rongyang Sun

2 4

Documentation for MPS data structure
by Amir M.Aghaei 04 Jan '18

04 Jan '18

Hello and happy new year! I would like to be able to save(load) MPS with the ALPS format so that I can: i) initiate DMRG with custom MPS derived from a different code, or to be able to ii) use the overlap function and compare results of separate code to those of ALPS. The question is whether there is already a standard way implemented for such activities and is it documented? Also, is there a documentation for how the ALPS-MPS is saved in HDF5 format? Amir

2 1