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Questions about t and t#
by 梁霄 01 May '16

01 May '16

Hello, In model.xml file, the Boson Hubbard model has the tunneling parameter "t", however in the bondterm "-t#*( bdag(i)b(j)+bdag(j)b(i) )" the parameter is defined as "t#" and its default value is zero. When the tunneling parameter is defined by "t" in python or command line, will it be any difference if I change the default value of "t#" into "t" in model.xml file? Thanks. Xiao Liang

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Help with install
by Thornton, Curtislee 30 Apr '16

30 Apr '16

Hello my name is Curtis, (My setup: Windows 10 pro 64bit, Python(x,y) which is python 2.7 32bit) I am trying to install ALPS and I am running into the problem with the PATH being too long. I read everything on the website and searched google and youtube for anything I can find but still nothing helps. I tried version 2.1 and 2.2 (32 and 64 bit versions) binary installer. I tried installing it to PATH from the beginning but get the error, I then tried installing it and adding to the PATH (through the windows setting) later (I tried adding every folder to the PATH seperatly as well) and still does not 'see' it when I try to "import pyalps" and tells me there is no module with that name. I also tried setting the path inside the program 'Spyder' (IDE) which I run python with. I also tried to copy and paste the files from the ALPS install into the C:\python27 folders that hold the same file types (Dlls, Lib, libs, and include). When I copy them over I then tried to "import pyalps" again and it finds the module but then throws an error saying that some other module was not found. Any help with this will be great. Thanks for your time. (Sorry if this is the second email, I sent the first before I was on the list and didn't know if it went through.)

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Three-Operator correlation in ED
by Hoi Yin Hui 20 Apr '16

20 Apr '16

Hi, I am aware that the mps codes can measure correlations with more than two operators, but it seems this is not supported in sparsediag codes. For example, when I enter 'MEASURE_CORRELATIONS[S3]':'Sz:Sz:Sz' and run sparsediag for a Heisenberg model, an error shows "Cannot evaluate expression - 0.5 * Sz:Sz(i)" Is there a way to compute this in ED? If this is not possible, I would like to know which part of the source codes of alps to modify so as to implement this myself.

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Convergence of mps_optim under PBC.
by Mateusz Łącki 19 Apr '16

19 Apr '16

Dear All, I am struggling with converging to the ground state of a BH model with unit filling with mps_optim with PBC. For low hopping it produces the same result as in the OBC case ignoring the boundary condition. I have the following input <pasted below>. The state to which the mps_optim converges: - has the same energy as the OBC hamiltonian for t<0.08 (the value of the constant varies it is larger for larger L) (see enclosed plot) and density artifacts at edges (similar to the OBC ground state) - If I observe how the energy of a minimized state varies as a function of sweep number, then there are “plateaus” (for several iterations the energy seems to be converged, then it jumps down).. It seems that for small t the GS computation of mps_optim is stuck at the first plateau. So for say t<0.07 after each sweep starting from 5 the energy is constant but for larger t, at say sweep number 10 there is a sharp drop. - none of the above happens for the OBC. - I include file containing the difference between the numerical result and the essentially exact result (strong coupling expansion up to 16th order - actually I copied the formula only until 10th order). Clearly for all t between 0 and 0.06 the results are wrong, then they are fine again (and start to depart for larger t again but this is because I was to lazy to copy higher orders too) - i have checked MAXSTATES=180 as well as MAXSTATES=320 (the results are exactly the same). For MAXSTATES=600 (and 120 sweeps and ietl_jcd_toll decreased to 1e-10) the results are almost the same again but now problems are for t<0.08 not for t<0.07 so in some sense situation is worse. *************** questions ****************** I have thus two questions: 1. Is there a way to resolve it? 2. It seems that propagation of the PBC across the sample length (L=40 sites) gets truncated somehow. Still increasing number of states to 600 did not help. Is it what is going on or is it a bug? Best, Mateusz Łącki ************* conf ****************** LATTICE="chain lattice" MODEL="boson Hubbard" L=40 MAXSTATES=180 measure_each=5 init_state="local_quantumnumbers" initial_local_N='1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1' nsweeps=60 t=0.06; U=1.0; N_total=40 Nmax=5; CONSERVED_QUANTUMNUMBERS='N' MEASURE[Entropy]=1 MEASURE_LOCAL[Local Density]='n' {}

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dwa cannot recognize hdf5 file
by 梁霄 18 Apr '16

18 Apr '16

Hello, I am using alps-2.2.b4, when it comes to recursiveRun of dwa the error occurs: XML tag expected. Therefore the recursiveRun abort immediately. It seems that the "dwa" cannot recognize hdf5 file format. Is there an alternative way? Xiao Liang.

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Warning with new HDF5 version
by Michele Dolfi 18 Apr '16

18 Apr '16

Dear ALPS users and developers, HDF5 1.10 has been released last month and it is always shipped with some packaging systems. ALPS got a small fix to compile with the new version, in case you need it please use the latest /trunk version. Please note that hdf5 1.10 is a major update and files written with it may not be readable by earlier versions such as 1.8.x. https://www.hdfgroup.org/newsletters/newsletter148.pdf ALPS is currently not yet using the new features explicitly, but we anyway advice to keep a consistent environment between your installations (cluster, workstation, etc) Best regards, Michele -- ETH Zurich Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland dolfim(a)phys.ethz.ch www.itp.phys.ethz.ch +41 44 633 78 56 phone +41 44 633 11 15 fax

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truncation error using mps_optim
by Forwordom 15 Apr '16

15 Apr '16

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

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Two questions about truncation error and entanglement entropy
by Forwordom 08 Apr '16

08 Apr '16

Dear, M. Dolfi I am a freshman about DMRG. I have two questions : (1) How to get truncation error using mps_optim codes ? (2) How to get von Neumann entanglement entropy S(A) of a system A. Actually, I have obtained entanglement entropy data by setting MEASURE[Entropy]=1 using mps_optim. For a spin chain, we got the data number of entanglement entropy which seems the same as the number of 'bond' in chain. For example, to run a mps_optim of a spin chain with 32 sites , I will get 31 data in output of entropy. What meaning of such entanglement entropy data? How to get von Neumann entanglement entropy S(A) of a two dimension system A (Just like page 5 in paper Phys.Rev.B 64,024424(2012)) L.J.Meng Xiangtan University ------------------

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rum dmft in parallel
by Wang Riping 04 Apr '16

04 Apr '16

Dear all, Can any one tell me how to run dmft calculation with parallel? There is no MPI parameter in pyalps.runDMFT. I tested dmft-02-dybridization in the tutorial. The manual states that the solver can be set as "mpirun -np process hybridization". But this way can not work to submit job to cluster. However, I need to use a bash file submit the job to cluster. Could anybody help me? Best regards. Riping Wang 2016.4.4 ******************************************* Mr. Riping WANG Postdoc Center for Superfunctional Materials, Advanced Material Research Building(Office-114), Ulsan National Institute of Science and Technology, UNIST-gil 50, Ulsan 44919, Republic of Korea. Tel:(+86) 13693675973 Email: wangriping(a)outlook.com<mailto:wangriping@outlook.com> Website: http://www.unist.ac.kr/ *******************************************

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A question about the boundary setting
by 北尘心 01 Apr '16

01 Apr '16

Dear all, I have a question about the boundary set.In the past, I use the boundary conditions is open boundary conditions in DMRG,but now i want to eliminate the impact of open boundary,so i need to use periodic boundary conditions.In the lattices file i find its setting ,like this: <LATTICEGRAPH name = "inhomogeneous chain lattice"> <FINITELATTICE> <LATTICE ref="chain lattice"/> <EXTENT dimension="1" size ="L"/> <BOUNDARY type="periodic"/> </FINITELATTICE> <UNITCELL ref="simple1d"/> <INHOMOGENEOUS><VERTEX/></INHOMOGENEOUS> </LATTICEGRAPH> but i still have a question about the accuracy of periodic boundary conditions,because i once read an paper on this question,it points out that DMRG offers much poorer results for problems with periodic boundary conditions (PBC) than for those with open boundary conditions(OBC),.The paper is attached. I wonder whether the problem has been solved. if yes,could you give me a paper with periodic boundary conditions to verify the correctness ? In addition,if i want to set a smooth boundary condition,what should i do in the lattices file? It is highly grateful for your any suggestions. Yours sincerely, Xingbo Wei Zhejiang Normal Universtiy, Jinhua, 230014, China

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