Dear Cristian,
From: Cristian Degli Esposti Boschi cristian.degliesposti@unibo.it Date: Thu, 15 Nov 2007 16:42:52 +0100
I would like to use ALPS to study a spin model defined on an open chain in which one or two sites in the middle of the chain can host "defects", for istance the local magnetic field and/or the exchange with neighbouring sites are different from all the other interactions in the chains.
The most straightforward way is specifying all the sites and bonds explicitly in the lattice XML file, e.g.
<GRAPH name="mylattice" vertices="8" edges="7"> <VERTEX id="1" type="0"/> <VERTEX id="2" type="0"/> <VERTEX id="3" type="0"/> <VERTEX id="4" type="1"/> <VERTEX id="5" type="0"/> <VERTEX id="6" type="0"/> <VERTEX id="7" type="0"/> <VERTEX id="8" type="0"/> <EDGE source="1" target="2" type="0"/> <EDGE source="2" target="3" type="0"/> <EDGE source="3" target="4" type="1"/> <EDGE source="4" target="5" type="1"/> <EDGE source="5" target="6" type="0"/> <EDGE source="6" target="7" type="0"/> <EDGE source="7" target="8" type="0"/> </GRAPH>
where a defect is at the 4th site on an 8-site open chain.
Best, Synge