November 2007 - Comp-phys-alps-users

DMRG question
by Justin David Peel 11 Dec '07

11 Dec '07

Hi all, I just have a quick question. How can I get the dmrg program to output the max truncation error during the final sweep (or any truncation error for that matter) to the output file? I know that it is output to the screen, but I would like it in the output file. Thanks, Justin

2 1

staggered magnetization: special definition of a bipartite lattice necessary?
by Björn Vogt 26 Nov '07

26 Nov '07

Hello, I am interested in using ALPS for Heisenberg systems including higher order on-site-anisotropies. To measure the staggered magnetization in an antiferromagnetic model: Do I have to define a special bipartite lattice or do the usual lattices in lattices.xml work? Yours, Björn Vogt -- Björn Vogt I. Institut für Theoretische Physik Universität Hamburg Jungiusstr. 9 Raum 122 040/42838-2056 http://www.physnet.uni-hamburg.de/hp/bvogt ____________________________________________________ This mail was sent through PHYSnet-WebMailer http://www.PHYSnet.uni-hamburg.de/mail

1 0

1D open chains with "defects"
by Cristian Degli Esposti Boschi 16 Nov '07

16 Nov '07

I would like to use ALPS to study a spin model defined on an open chain in which one or two sites in the middle of the chain can host "defects", for istance the local magnetic field and/or the exchange with neighbouring sites are different from all the other interactions in the chains. Can it be done by proper definitions in the lattice.xml file? (and of course then also in models.xml) Thanks a lot for your work. Cheers, Cristian -- ___________________________________________________ Cristian Degli Esposti Boschi CNR, CNISM, Unita' di Ricerca di Bologna, c/o Dipartimento di Fisica, Universita' di Bologna viale Berti-Pichat, 6/2, 40127, Bologna, Italia tel. ++39 051 2095114 fax ++39 051 2095113 e-mail: cristian.degliesposti -AT- unibo.it web: http://www.df.unibo.it/ricerca-01/theory ___________________________________________________

2 1

Magnetization histogram from exact diagonalization?
by Austen Lamacraft 07 Nov '07

07 Nov '07

Hello, Is there a simple way to get at the histogram of the distribution of the magnetization in the ground state of (say) the transverse field Ising model? Or failing that, a way to get out the full ground state eigenvector obtained by exact diagonalization? A related question: Is there a simple way to take the expectation value of an arbitrary function of spin at a single site in Monte Carlo? I guess this comes under "Definition of custom measurements", and that tutorial isn't finished yet. Thanks, Austen

1 0

dmrg tutorial example is not running
by Aniket Kulkarni 03 Nov '07

03 Nov '07

Hi all, I am trying to run dmrg tutorial example but it is showing error. The error is as follows: $ simple_dmrg <parm1 error: ALPS noninteractiong DMRG application version 1.0 available from http://alps.comp-phys.org/ copyright (c) 2003-2004 by Salvatore R. Manmana <Salva(a)theo3.physik.uni-stuttg art.de> Reinhard M. Noack <Reinhard.Noack(a)physik.uni-marbur g.de> Ian McCulloch <ianmcc(a)physik.rwth-aachen.de> for details see the publication: F. Alet et al., Report cond-mat/0410407. EXCEPTION: bad lexical cast: source type value could not be interpreted as target t Please see the error and tell me the problem. Thanks in advance with regards, Aniket

2 2