I think you can solve this bug by removing the last line " <EDGE type="0"><SOURCE vertex="1" offset="1"/><TARGET vertex="2" offset="1"/></EDGE>

" from the definition of the UNITCELL.

Step 1: Expose the bug.

You can write a short "mock" python script to generate a simulation input XML file. Here is the script (named get_config.py)

-------------------------------

import pyalps

p = {}

p['LATTICE'] = '2 band sublattice open chain lattice'

# p['LATTICE'] = '2 band open chain lattice'

p['LATTICE_LIBRARY'] = './lattices.xml'

p['L'] = 4

pyalps.writeInputFiles('superlatticechain', [p])

-------------------------------

where your own lattice library file is at './lattices.xml'. Then run the script and get the input xml file:

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~ alpspython ./get_config.py

~ ls

ALPS.xsl lattices.xml superlatticechain.task1.in.xml

get_config.py superlatticechain.in.xml

-------------------------------

Then use the command line tool 'printgraph' to print the GRAPH used by your simulation:

-------------------------------

~ printgraph superlatticechain.task1.in.xml

<EDGE source="3" target="4" id="4" type="0" vector="0"/>

<EDGE source="5" target="6" id="7" type="0" vector="0"/>

<EDGE source="7" target="8" id="10" type="0" vector="0"/>

</GRAPH>

-------------------------------

You will see that some bonds are duplicated constructed (in bold).

Step 2: Fix the bug.

The removed line in your UNITCELL definition leads to this duplicated construction. Because this line creates a type 0 bond from the vertex 1 with offset 1 to the vertex 2 with offset 1. The two vertexes are shifted 1 unit cell. That means create a bond in the next unit cell of the LATTICE. This is the source of the redundancy. After fixing the bug, you can print the right result:

-------------------------------

</GRAPH>

-------------------------------

Hello everybody,

I was trying to run a simulation on the one-dimensional superlattice Bose-Hubbarad with alternating tunneling rates t1 and t2, which is the bosonic analogue of the Su-Schrieffer-Heeger(SSH) model. The lattice with one unit cell is made of A and B sites.

To this end, I have adaped the following unit-cell:

This enters into the lattice graph:

And the Hamiltonian:

<HAMILTONIAN name="boson Hubbard">
<PARAMETER name="mu" default="0"/>
<PARAMETER name="hop" default="1"/>
<PARAMETER name="hop'" default="1"/>
<PARAMETER name="U" default="0"/>
<BASIS ref="boson"/>
<SITETERM site="i">
    <PARAMETER name="mu#" default="mu"/>
    <PARAMETER name="U#" default="U"/>
    -mu#*n(i)+U#*n(i)*(n(i)-1)/2
</SITETERM>
   <BONDTERM type="0" source="i" target="j">
     -hop*boson_hop(i,j)
   </BONDTERM>
   <BONDTERM type="1" source="i" target="j">
     -hop'*boson_hop(i,j)
   </BONDTERM>
</HAMILTONIAN>

However when I run a DMRG calculation.I still get the wrong results.I compare the ground state energy of it with which I calculated by matlab using ED method.All the parameters of the two calculation are the same.

I seem to misunderstand the implementation. So the question I want to ask is that are there any wrong in the definitions of my lattice or the model in XML.

Thank you for any kind of heplful remarks.

Yulian Chen