Dear Dolfi,
Recently, I've been using the dmrg and mps_optim two algorithms provided by ALPS 2.2.0 to calculate some properties for the same quantum systems. Then, I have compared the truncation error part of outputs from two algorithms. I have two questions about truncation error:
(1)Firstly,I've noticed that the value calculated for the truncation error comes out to be zero for some of the iterations. It seems to occur on any DMRG programs I run, even the simple ones provided in the DMRG tutorials. Is this result correct?
(2)Secondly,I can find final truncation error in *.out.xml file if using dmrg algorithm, but can not find this value when using mps_optim algorithm. How to get final truncation error for a run using mps_optim. Actually, I hope to control truncation error by adjusting the number of sweeps and the number of states kept.
Any insight and advice is much appreciated. Thanks.
Lijun Meng Xiangtan University, Hunan Pro, China