Dear ADRIAN
I used Sz_total=N(S1-S2),as an input parameter but this thing just speed up the calculation and it doesn't any effect on the output,means that with this input parameter i have result that it doesn't differ with the result that earlier i have got.i want to achieve the results that earlier are achieved in the following paper,
(SK Pati, S Ramasesha, D Sen - Physical Review B, 1997 - APS)
they study the ferrimagnetic chain and present the ground state energy and some correlations.
they consider N cell that each cell consist of two spin(s1,s2).
Hamiltonian is H=sum_i (S2_i . S1_i+1)+(S1_i.S2_i -1)
i counts the cells and it is form 0 to N.
the results that i achieve,two digite concur with theirs results.
I don't what must i do that i have a better results.
Thanks
On Wed, Oct 15, 2008 at 3:00 AM,
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Today's Topics:
1. Ferrimagnet (zhian asadzadeh)
2. Re: Ferrimagnet (Adrian E. Feiguin)
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Message: 1
Date: Tue, 14 Oct 2008 19:02:01 +0330
From: "zhian asadzadeh" <zhian.asadzadeh@gmail.com>
Subject: [ALPS-users] Ferrimagnet
To: Comp-phys-alps-users@phys.ethz.ch
Message-ID:
<89e5d6760810140832p1dec90d9h3dfb0cab0d2367ee@mail.gmail.com>
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Dear All
I'm making my first experiments with Alps...
I want to use DMRG for ferrimagnetic chain,but i have some problems.
First,in the dmrg steps because the chain don't have the symmetry between
left and right halves,the density matrices for these two halves should be
constructed at every iteration of the calculation.
Second,I think that it isn't exist spin parity symmetry.
How i can do these?
Thanks in advance
zhian
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Message: 2
Date: Tue, 14 Oct 2008 15:16:53 -0700
From: "Adrian E. Feiguin" <afeiguin@kitp.ucsb.edu>
Subject: Re: [ALPS-users] Ferrimagnet
To: comp-phys-alps-users@phys.ethz.ch
Message-ID: <48F51A55.7080902@kitp.ucsb.edu>
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Dear Zhian
>
> I'm making my first experiments with Alps...
> I want to use DMRG for ferrimagnetic chain,but i have some problems.
> First,in the dmrg steps because the chain don't have the symmetry
> between left and right halves,the density matrices for these two
> halves should be constructed at every iteration of the calculation.
This is not quite right. You can use DMRG in disordered systems if you
wish. Try it out as it is.
> Second,I think that it isn't exist spin parity symmetry.
Sztot is a well defined quantum number in ferrimagnetic spin chains. You
can determine the value for the ground state and use it as an input
parameter.
I hope this helps.
If you have further questions, it would be very helpful if you could
direct us to a paper with the Hamiltonian written explicitly
Saludos,
<ADRIAN>
End of Comp-phys-alps-users Digest, Vol 31, Issue 4
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