[ALPS-users] measuring truncation errors in mps_optim

[Robertson Esperanza]

Thank you for all the help so far, now I'm trying to check for convergence
of my results.

First, is it enough to just check how the truncation error changes with
sweeps (at a certain MAXSTATE value) or I need to both check the iteration
history of the ground state energy and the truncation error?

Second, checking the supplementary materials provided (Computer Physics
Communications 185 (2014) 3430–3440) for the Hubbard ladder, why are there
381 values of energy and truncation weights for every iteration? Why is the
total truncation error for that iteration is the sum of all the 381
truncation weight values (based on iteration.py)? How is truncation error
defined (e.g. is it 1 - sum of all reduced density eigenvalues
corresponding to all the picked states?) ?

 As far as I understand the DMRG algorithm every iteration/sweep has a
corresponding bond dimension in which as you progress through iterations
(until you reach the "SWEEPS"th iteration), bond dimension increases until
you reach "MAXSTATES" at the "SWEEPS"th iteration.

Regards,
Robertson Esperanza
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