Comp-phys-alps-users

comp-phys-alps-users@lists.phys.ethz.ch

June 2009

8 participants
12 discussions

how to find the basis vector for a particular eigenvalue
by khalid hassan 03 Jun '09

03 Jun '09

Dear alps team I am using the alps program print_numeric to find the basisvectors and hamiltonian matrix of the system. What I want to know is the energy eigenstate of the corresponding basis vectors. I use the fulldiag program to find the energyeigenstates. how I know which enegy states corresponds to which basisvector. As the output in the fulldiag program is divided into Total_Momentum quantum number (0,0) (Pi,0) (0,Pi) (Pi,Pi), I tried to restrict the printnumeric output by fixing the quantum number TOTAL_MOMENTUM="0 0", but it did not work and as got all the basis vectors and basis states. Since it is very necessary for me to know the lowest energy basis states, please suggest a solution. my program for print_numeric is as under LATTICE_LIBRARY = "../../lib/xml/lattices.xml" MODEL_LIBRARY = "../../lib/xml/models.xml" LATTICE = "square lattice" CONSERVED_QUANTUMNUMBER="N" TOTAL_MOMENTUM="0 0" N_total=4 L = 2 U =0 mu = 0 t = 1 t0=0 t1=0 MODEL = "alternative fermion Hubbard" the outputvectors are like this [ |0 0 0 0 > |0 0 0 0 > |1 1 2 0 > |1 1 2 0 > ] which i suppose is spin up, spin down, total particles, total spin how can we find the total momentum of the above state. if you say something about total momentum it will be appreciated. So my problem is to find the basis states of lowest eigenvalues. how can I find them using alps. Thanks best regards khalid loane

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Setting up polaritonic model in ALPS
by Su Chun-Hsu 03 Jun '09

03 Jun '09

Dear all, I'm new to using ALPS and not entirely confident with setting up my model, which didn't appear to work at the moment. I'm interested in polaritonic system -- evanescently coupled-cavity system, each cavity containing a two-level atom. I have set up my model in the attached xml, Sminus and Splus are atomic projection operators and b are photon annihilation operator. The total number of excitations (atomic and photonic) is conserved. When I try running it, there is an bad_alloc error. Will anyone be kindly give me some pointers? Much appreciated and thank you very much in advance. Regards, Chun-Hsu, Su _________________________________________________________________ Looking to move somewhere new this winter? Let ninemsn property help http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Fninemsn%2Edomain%2Ecom%2Eau…

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