Dear Prof. Dr. M. Troyer,

Thank you very much for your reply.  I do set the “Sz” as a conserved quantum number since I just used the file I wrote 
for the the general Hubbard model. I think it is just the cause. Thank you very much. 

With best wishes,
Ahai Chen   



On Thu, Mar 21, 2013 at 9:07 AM, Matthias Troyer <troyer@phys.ethz.ch> wrote:
On Mar 14, 2013, at 7:00 AM, Chen Ahai <chenahaiphysics@gmail.com> wrote:

Dear all,

I am trying to add the spin-orbit coupling term to the 1D Hubbard model. I use the standard files 
for 1D Hubbard model in the library and add those codes: 
-----------------------------------------------------------------------------------
<BONDOPERATOR name="SOC" source="x" target="y">
  cdag_up(y)*c_down(x)-cdag_down(y)*c_up(x)+cdag_down(y)*c_up(x)-cdag_up(y)*c_down(x)
</BONDOPERATOR>
-----------------------------------------------------------------------------------
and 
-----------------------------------------------------------------------------------
  <BONDTERM source="i" target="j">
    <PARAMETER name="t#" default="0"/>
    <PARAMETER name="alpha" default="0"/>
    -t*fermion_hop(i,j)-alpha*SOC(i,j) 
  </BONDTERM>
-----------------------------------------------------------------------------------
to the model XML file just like before. But it seems it does not work. The results keep the same 
when I change the parameter 'alpha' .

Can you give me some advices ? Thank you very much in advance.

As usual, without full inputs and scripts nobody will be able to really tell you what is happening. My conjecture is that you have declared Sz as a conserved quantum number, and then this term actually never acts.




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Ahai Chen
Department of Physics, Zhejiang Normal University
Jinhua, Zhejiang Province, 321004, China
e-mail: chenahaiphysics@gmail.com;
              chenahai@yahoo.cn
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