September 2014 - Comp-phys-alps-users

dmrg
by Mateusz Łącki 13 Sep '14

13 Sep '14

Dear All, I am still using alps-dmrg for my computation - mps_optim is giving me some troubles, that I will describe later in a separate email. Is is possible to ask the dmrg application to clean its temporary files after computation is done? the folder which I have specified using TEMP_DIRECTORY=/home/lacki/tmp/ is filled with old data. Of course I could write a script that checks launch date of each of „dmrg“ processes currently running and deletes all older files, but it seems really cumbersome. Kind Regards, Mateusz Łącki

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memory usage in DMRG
by Mateusz Łącki 11 Sep '14

11 Sep '14

Dear All, I have been running the following input: <pasted at the bottom> I have observed that for Bose-Hubbard model on chain of length L=256, unit filled, under open boundary conditions the DMRG code uses over 32G memory (this is the hardware limit, it clearly wants more, for L=128 it was around 20G). is that normal? I would estimate that an MPS state of 256 sites, with bond dimension 60, local Hilbert space 7 should be much smaller (even if we allow for a small constant factor for temporary data) Kind Regards, Mateusz Łącki LATTICE="open chain lattice" MODEL="boson Hubbard" SWEEPS=8 Nmax=6 NUMBER_EIGENVALUES=1 L=256 CONSERVED_QUANTUMNUMBERS="N" N_total=256 VERBOSE=0 t=0.25 U=1 mu=0 {MAXSTATES=60}

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additional update
by tesfaye mamuye 10 Sep '14

10 Sep '14

Dear ALPS Developers/users I am using alps CT-QMC(Hybridization expansion) as impurity solver. But the total acceptance rate is getting low and low, and I'm wondering if it may affect the final result. In order to overcome this, I'm thinking to use additional update: 'shift of the segment end point' which is used to enhance the sampling efficiency (to increase the acceptance ratio and reduce auto-correlation times) which do not change the expansion order. However, I didn't get in the documentation on how to implement this additional update as control parameter 'SPINFLIP'={0.1} : specify to whether to perform spin flip update. Is it possible to use for shift of the segment end point update 'N_SHIFT'=1 ? I need help on how to implement this additional update. here is the sample |------ Simulation details (master only) after 2665880 sweeps ------| Total acceptance rate = 22.92% Individual acceptance rate for update change zero state = 0.00% (proposal rate = 10.00%) insert segment = 6.37% (proposal rate = 25.00%) remove segment = 6.37% (proposal rate = 25.00%) insert anti-segment = 5.09% (proposal rate = 20.00%) remove anti-segment = 5.09% (proposal rate = 20.00%) swap segment = 0.00% (proposal rate = 0.00%) |-----------------------------------------------------------------| Thank you for your time

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Help with LiveALPS
by Niraj Ghimire 10 Sep '14

10 Sep '14

Dear ALPS users, I have been running LiveALPS from my USB flash drive and I can't get access to the internet. I could not find any information anywhere on how to resolve this issue. Would you be able to help me out ? ~Niraj

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(no subject)
by hamid mosadegh 07 Sep '14

07 Sep '14

Dear All What is the momentum of , E_1(N_{\uparrow},(N_{\downarrow} ,L), the lowest-excitation energy in the Hubbard model in the S=0 sector. I means, I want to evaluate the velocity of charge excitation from E_1(N_{\uparrow},(N_{\downarrow} ,L)- E_0(N_{\uparrow},(N_{\downarrow} ,L) where E_1(N_{\uparrow},(N_{\downarrow} ,L) is the lowest-excitation energy with momentum k=2\pi/L and total spin S=0. If i run MODEL="fermion Hubbard" CONSERVED_QUANTUMNUMBERS="Nup,Ndown" Ndown_total=10;Nup_total=10 NUMBER_EIGENVALUES=2 what is the momentum of first excitation. is it possible to determine or change it? thanks H. Mosadeq Shahr-e-Kord University (SKU), Shahr-e-Kord , Iran

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the parity sector in DMRG
by hamid mosadegh 03 Sep '14

03 Sep '14

Dear all Is it possible to do the DMRG or ED calculations of fermion Hubbard model in the odd(even) parity sector using ALPS? I need to determine the minimum energies for eigenstates in the even and odd parity sectors. Thanks -- H. Mosadeq Shahr-e-Kord University (SKU), Shahr-e-Kord , Iran

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parallel calculation on Windows
by orchidwood 01 Sep '14

01 Sep '14

Dear all, Can the ALPS on 64-bit Windows 7 do parallel calculation with Vistrail system? If it can do this, how?Thanks,Mu Lan

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