Dear Cathy,

I’m not sure I fully get what if your goal. Here is anyway what I would do.

Usually for inhomogeneous models we define lattice sites with different type and set different values of the model parameters for each type.

Quick example:

In mylattice.xml you define the graph

<LATTICES>
 <GRAPH name="my great lattice" dimension="1" vertices=“3" edges="2">
  <VERTEX id="1" type="0"><COORDINATE>0</COORDINATE></VERTEX>
  <VERTEX id="2" type="1"><COORDINATE>1</COORDINATE></VERTEX>
  <VERTEX id="3" type=“2"><COORDINATE>2</COORDINATE></VERTEX>
  <EDGE source="1" target="2" id="1" type="0" vector="1"/>
  <EDGE source="2" target="3" id="2" type="0" vector="1"/>
 </GRAPH>
</LATTICES>

In the parameter file:

LATTICE_LIBRARY="mylattice.xml"
LATTICE="my great lattice"

MODEL=“fermion Hubbard” 

t=1

U=8

mu0=0

mu1=10

mu2=5

This will have a different chemical potential for each of the three sites.

Best regards,

Michele

--

ETH Zurich

Michele Dolfi

Institute for Theoretical Physics

HIT G 32.4

Wolfgang-Pauli-Str. 27

8093 Zurich

Switzerland

dolfim@phys.ethz.ch

www.itp.phys.ethz.ch

+41 44 633 78 56 phone

+41 44 633 11 15 fax 

On 01 Jun 2015, at 18:31, Cathy Wu <cathy.em2013@gmail.com> wrote:

Dear everyone,

Does anyone know how to use the "coordinate " parameter in the models.xml file.

I am trying to defining a quasi-periodic potential. But the "sparsediag" function does not recognize site "i".

best regards!