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unit of temperature in the extended bose-hubbard model
by Fu-Jiun Jiang ITP 25 Jan '10

25 Jan '10

hello In the extended bose-hubbard model, what's the unit for the temperature T? Is it true that when one lets V = 1 (V is the nearest-neighbor repulsive interaction), then T = 0.01 really stands for T = 0.01/V? Thanks. Sincerely, Fu-Jiun

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full diagonalization with antiperiodic BCs
by jessica.alfonsi＠unipd.it 20 Jan '10

20 Jan '10

Hi everyone, I have posted some days ago about full diagonalization with antiperiodic boundary conditions for a Hubbard chain but I havent't received no answer yet. Maybe I was not much clear with my question. The point with my question is that I'd like to specify antiperiodic boundary conditions for some specific sites (i.e. a bond term t#*fermion_hop(1,N), where sites 1 and N are the chain ends) in the input model xml file. This means that the terms related to boundary conditions have to be specified separately from the usual bond terms with fermionic hopping. Is it possible to do that in the xml model file ? How can I do that in a C++ code compiled against ALPS libraries ? This would be very important for specifying lattices and models with the highest flexibility, since later I'd like to write a matrix free ED code for my 2D custom lattice... Could you give me some insight please ? Best regards Jessica Alfonsi -- Dr.ssa Jessica Alfonsi Dipartimento di Scienze Chimiche Università di Padova via Marzolo 1 35100 Padova (Italy) +39 0498275726 e-mail jessica.alfonsi(a)unipd.it

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Spliting total energy
by Akinlolu Akande 19 Jan '10

19 Jan '10

Hi all, Is it possible to split the total energy calculated by alps into their individual components? For example, in the case of the Hubbard model I will want to know how to split the kinetic energy and the potential energy terms in ALPS code.u know the total hamiltonian H=H_hopping(Kinetic term)+H_U(potential term), when one does the exact diagonization or DMRG,it gives the total energy but I want to calculate the individual energy. Can anyone help? Thanks. Akin

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exact diagonalization with antiperiodic BCs
by jessica.alfonsi＠unipd.it 18 Jan '10

18 Jan '10

Dear ALPS team, I have successfully performed a full diagonalization for a Hubbard chain with periodic boundary conditions using the included models in xml files. Now, I'd like to perform the same task with antiperiodic boundary conditions (a fermionic hopping with opposite sign) at chain ends, or more generally with exponetial complex phase, possibly by using again the xml input schema. Can you give me some hint ? Is it also possible to specify the hamiltonian or any other operator in a more extended form, with the site indices explicitly defined in the expression, as one would do with Mathematica, such as for instance -t#*fermion_hop(1,2) + t#*fermion_hop(3,4) + ... and so on ? Thank you for your support Best regards Jessica Alfonsi

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Classical MC for
by Andrew James 15 Jan '10

15 Jan '10

Hi, I'd like to use the classical Monte Carlo code to study the properties of the 'Heisenberg-XY' model, where the symmetry is a product of O(3) and O(2), i.e. the degrees of freedom at each site can be represented by (n, \theta) where n is a vector and \theta is an independent angle. Is it feasible to do this by editing the current mc/spin files alone? From inspection it seems that, at the very least, I would need to change parts of spinmc_factory.C and create something similar to the file on.h, but allowing for O(a) * O(b) symmetry. Thanks for any advice you can give, Andrew

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Full diagonalization for fixed N
by Mykola Maksymenko 14 Jan '10

14 Jan '10

Dear all, I perform a full diagonalization of Hubbard hamiltonian using a fulldiag application. I'm interested in energy spectrum for low densities of electrons only, or even fixed number of electrons on the lattice. So I don't really need to go over all subspaces with number of electrons N=0..N_total. I would be tankful for a hint where and how can I modify the code to fix the N? :) Best regards, Mykola

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Bls: Comp-phys-alps-users Digest, Vol 46, Issue 3
by Muhammad Rofiq 06 Jan '10

06 Jan '10

I had used T in Kelvin and H in Tesla,, What is the dimension for magnetization and suceptibility? I so confuse about it..... Menambah banyak teman sangatlah mudah dan cepat. Undang teman dari Hotmail, Gmail ke Yahoo! Messenger sekarang! http://id.messenger.yahoo.com/invite/

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dimension
by Muhammad Rofiq 06 Jan '10

06 Jan '10

Dear all,, I had running my reaserch using ALPS program in 1D Heisenberg Models, when I have plotting the results (susceptibilty vs Temperature & Magnetization vs Magnetic Field) it was no Dimension unit. Can tell me about the dimension unit of my results? thanks before,, Apa dia selingkuh? Temukan jawabannya di Yahoo! Answers. http://id.answers.yahoo.com

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Zinc blende
by Muhammad Rofiq 02 Jan '10

02 Jan '10

Dear all, I have some probelm to make an XML for fcc lattice of Zinc blende. I had simulated it using Heisenberg model S=1/2, but it can't synchron with the experiment. I get the Neel temperature 10K and the experiment 40K. Can do you help me about it? Apakah saya bisa menurunkan berat badan? Temukan jawabannya di Yahoo! Answers! http://id.answers.yahoo.com

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Worm Algorithm Question
by Snir Gazit 02 Jan '10

02 Jan '10

Hi, I am implementing the worm algorithm for the Bose Hubbard model. On of the "worm moves" is to insert a kink after the MASHA head this can cause a reconnection of the worm. I think that this move is possible only when there is a world line in the target site, other wise there is nothing to connect to. I tried to see were this condition is implement in the code but I failed to find it. I'll be grateful if someone can direct me to the location of this condition in the code, or tell me were my reasoning is wrong (may be there is some other way to close the world line). Thanks in advance Snir

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