Hi Dear,
I tried to calculate energy gap for ferrimagnetic ladder. in this paper ( Phy Rev B, 63, 054432) it has been done which you can find in table I. I used the periodic boundary condition because in the case of open boundary condition the energy converges very slowly. I have achieved the following result. E0= -0.757036 E1= -0.757032
I have used the following input file: I have tried for inter chain coupling J' = 0.2 with the notation of this paper.
LATTICE="ferrimagnetic ladder" SWEEPS=4 MAXSTATES=300 MODEL="spin", L=30 local_S0=1/2,local_S1=1,Jxy0=1,h=0.0,Jxy1=0.2,Jz1=0.2 BC1=periodic,BC2=periodic NUMBER_EIGENVALUES=2 Jz0=1 {Gamma=0.0;}
which L is the number of unit cell and h, Gamma are longitudinal and transverse magnetic field respectively. Jz0 , Jxy0 are chain couplings and Jz1, and Jxy1 are inter chain couplings. we see that the result is not concur with this paper for energy gap. I see in this paper lanczos method is used but I expect that the result be same in 4 digit. please let me know what is wrong?
Thanks, Mohammad.
On Wed, Mar 18, 2009 at 2:30 PM, comp-phys-alps-users-request@phys.ethz.chwrote:
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Today's Topics:
- Energy Gap (zhian asadzadeh)
- Re: Energy Gap (Matthias Troyer)
Message: 1 Date: Tue, 17 Mar 2009 14:43:46 +0330 From: zhian asadzadeh zhian.asadzadeh@gmail.com Subject: [ALPS-users] Energy Gap To: comp-phys-alps-users@phys.ethz.ch Message-ID: 89e5d6760903170413w7e72ef85i873b8d47564f4320@mail.gmail.com Content-Type: text/plain; charset="iso-8859-1"
Hi Dear,
Thank you for your consideration. My model is anisotropic Ferrimagnetic chain in transverse magnetic field. when I say the result is wrong I mean when I have tried to obtain energy gap for some problems and models which have been solved earlier I saw the result doesn't agree with those earlier results. for example spin one and half-one chain and ferrimagnetic chain and anisotropic ferrimagnetic ladder. Something is not very obvius for me, how DMRG calculate ground state and first exited state from one wave function ?!
Thanks, Zhian.
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- Re: Energy Gap (Matthias Troyer)
Message: 1 Date: Mon, 16 Mar 2009 12:33:11 -0700 From: Matthias Troyer troyer@phys.ethz.ch Subject: Re: [ALPS-users] Energy Gap To: comp-phys-alps-users@phys.ethz.ch Message-ID: 43E825E5-7BE3-4EA0-9C2A-20A1FC8C21AF@phys.ethz.ch Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
On Mar 16, 2009, at 2:01 AM, zhian asadzadeh wrote:
Hi All,
I want to calculate energy gap for spin chain with DMRG. I set NUM_EIGENVALUES=2 in my parm file but the result which achieved is wrong. Is it necessary to determine something else for example the sector which DMRG work in it? in my problem I dont have any good symmetry and I can not easily determine the sector which the first exited state is in it. I would be very appreciate if someone could please help me.
Thanks, Zhian.
Can you please send more details about your model, or better yet the input file? An what do you mean exactly by saying that the result is wrong?
Matthias
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