March 2007 - Comp-phys-alps-users

MC heisenberg follow up/ lattices
by David Miller 09 Apr '07

09 Apr '07

Hi, Thanks for the reply. I would also like to know if the anisotropy can be varied throughout the lattice, i.e. different values for different sites, or is only one value throughout the whole lattice allowed? Additionally I would like some points regarding the lattice definitions to be confirmed. 1. The edge type 0,1,2 corresponds to bond type J0, J1 ,J2 parameters? Edge type default = 0? 2. The edge offset is in units of 'basis vectors' specified in the <BASIS> tags? Default = 0 0 0? Allowing both -ve and +ve numbers? Thanks, David Miller >From: comp-phys-alps-users-request(a)phys.ethz.ch >Reply-To: comp-phys-alps-users(a)phys.ethz.ch >To: comp-phys-alps-users(a)phys.ethz.ch >Subject: Comp-phys-alps-users Digest, Vol 12, Issue 2 >Date: Wed, 28 Mar 2007 12:00:02 +0200 > >Send Comp-phys-alps-users mailing list submissions to > comp-phys-alps-users(a)phys.ethz.ch > >To subscribe or unsubscribe via the World Wide Web, visit > https://webmail.phys.ethz.ch/mailman/listinfo/comp-phys-alps-users >or, via email, send a message with subject or body 'help' to > comp-phys-alps-users-request(a)phys.ethz.ch > >You can reach the person managing the list at > comp-phys-alps-users-owner(a)phys.ethz.ch > >When replying, please edit your Subject line so it is more specific >than "Re: Contents of Comp-phys-alps-users digest..." > > >Today's Topics: > > 1. Re: Classical MC Heisenberg help (Matthias Troyer) > > >---------------------------------------------------------------------- > >Message: 1 >Date: Tue, 27 Mar 2007 17:23:54 +0200 >From: Matthias Troyer <troyer(a)phys.ethz.ch> >Subject: Re: [ALPS-users] Classical MC Heisenberg help >To: comp-phys-alps-users(a)phys.ethz.ch >Message-ID: <531DC60A-E501-4263-ACD0-ECD3FF56F0CB(a)phys.ethz.ch> >Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed > >It should work by specifying the parameter > >D="0 0 1" > >The three components are Dx, Dy and Dz. Please be aware however that >in that case only local updates can be used. > > >Matthias > > >On Mar 27, 2007, at 1:30 AM, David Miller wrote: > > > Dear all, > > > > I am doing classical MC simulations using the Heisenberg model with > > Alps-1.3b2. I would like to include an easy axis/plane anisotropy > > in the Heisenberg Hamiltonian of the form (-/+)D*sum_i((Sz_i)^2), > > how would I acheive this? > > > > Thanks, > > > > David Miller > > > > _________________________________________________________________ > > Solve the Conspiracy and win fantastic prizes. http:// > > www.theconspiracygame.co.uk/ > > > >End of Comp-phys-alps-users Digest, Vol 12, Issue 2 >*************************************************** _________________________________________________________________ Solve the Conspiracy and win fantastic prizes. http://www.theconspiracygame.co.uk/

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Re: [ALPS-users] changing parameters in ALPS
by Matthias Troyer 29 Mar '07

29 Mar '07

Hi Aniket, The answer is simple: add a line like S=2 to the parameters. However there should generally be no need, since the value of S can just be absorbed into the coupling constant. Best regards Matthias On 29 Mar 2007, at 20:50, aniket(a)jncasr.ac.in wrote: > Respected sir, > I am new user of ALPS. So can I ask you one query? > > How change the value of S in 1D Heisenberg model? > > Hamiltonian for 1D Heisenberg model > > H = sum (S(i)*S(j)) > > description > > here H is the Hamiltonian > > sum means summation over all i & j. > > S(i) and S(j) means i & j th spin. > > by default S value is 1 for classical CONVENTION. > how change this value (other than 1)? > > I am running alps-application/tutorial/classical2/parm2a file. > > ( for convenience I am attaching URL also > http://alps.comp-phys.org:16080/mediawiki-1.9.3/index.php/ > Tutorial:ClassicalMCSimulations#The_one-dimensional_Heisenberg_chain ) > > I am waiting for your reply. > > Regards, > Aniket

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Classical MC Heisenberg help
by David Miller 27 Mar '07

27 Mar '07

Dear all, I am doing classical MC simulations using the Heisenberg model with Alps-1.3b2. I would like to include an easy axis/plane anisotropy in the Heisenberg Hamiltonian of the form (-/+)D*sum_i((Sz_i)^2), how would I acheive this? Thanks, David Miller _________________________________________________________________ Solve the Conspiracy and win fantastic prizes. http://www.theconspiracygame.co.uk/

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