Dear All,

I am trying to run the QMC "loop" code for the Kitaev honeycomb model which is actually an XYZ two-spin interaction on a honeycomb lattice with three different link types i.e. x,y and z.

The parameter file that I use is defined as:

parms = []
for t in [0.05, 0.1, 0.2, 0.3]:
   parms.append(
       {
         'LATTICE'        : "honeycomb kitaev lattice",
         'T'              : t,
         'Jx'             : .1 ,
         'Jz'             : .1 ,
         'Jy'             : .1 ,
         'ALGORITHM'      : "loop",
         'THERMALIZATION' : 65536/8,
         'SWEEPS'         : 65536,
         'MODEL'          : "K-H",
         'L'              : 4
       }
   )


The model that I use is defined as:

<HAMILTONIAN name="K-H">
  <PARAMETER name="Jz" default="0"/>
  <PARAMETER name="Jx" default="0"/>
  <PARAMETER name="Jy" default="0"/>
  <PARAMETER name="hx" default="0"/>
  <PARAMETER name="hz" default="0"/>
  <BASIS ref="spin"/>
  <SITETERM site="i">
    -hz*Sz(i)-hx*Sx(i)
  </SITETERM>
   <BONDTERM type="0" source="i" target="j">
    Jz*Sz(i)*Sz(j)
  </BONDTERM>
   <BONDTERM type="1" source="i" target="j">
    Jx*Sx(i)*Sx(j)
  </BONDTERM>
  <BONDTERM type="2" source="i" target="j">
    Jy*Sy(i)*Sy(j)
  </BONDTERM> 
</HAMILTONIAN>


and the lattice is defined as:

<UNITCELL name="honeycomb inhomogeneous" dimension="2">
  <VERTEX><COORDINATE>0 0</COORDINATE></VERTEX>
  <VERTEX><COORDINATE>-0.288665771484375 0.5773468017578125</COORDINATE></VERTEX>

  <EDGE type="0"><SOURCE vertex="1"/><TARGET vertex="2"/></EDGE>
  <EDGE type="1"><SOURCE vertex="2"/><TARGET vertex="1" offset="0 1"/></EDGE>
  <EDGE type="2"><SOURCE vertex="1"/><TARGET vertex="2" offset="1 -1"/></EDGE>
</UNITCELL>

<LATTICEGRAPH name = "honeycomb kitaev lattice">
  <FINITELATTICE>
    <LATTICE ref="triangular lattice"/>
    <PARAMETER name="W" default="L"/>
    <EXTENT dimension="1" size="L"/>
    <EXTENT dimension="2" size="W"/>
    <BOUNDARY type="periodic"/>
  </FINITELATTICE>
  <UNITCELL ref="honeycomb inhomogeneous"/>
</LATTICEGRAPH>


when I run the simulation with the "loop" code, the following message is produced and the simulation stops:

  multi-cluster quantum Monte Carlo algorithms for spin systems
  available from http://wistaria.comp-phys.org/alps-looper/
  copyright (c) 1997-2010 by Synge Todo <wistaria@comp-phys.org>

using ALPS/parapack scheduler
  a Monte Carlo scheduler for multiple-level parallelization
  copyright (c) 1997-2013 by Synge Todo <wistaria@comp-phys.org>

based on the ALPS libraries version 2.2.b3
  available from http://alps.comp-phys.org/
  copyright (c) 1994-2013 by the ALPS collaboration.
  Consult the web page for license details.
  For details see the publication:
  B. Bauer et al., J. Stat. Mech. (2011) P05001.

[2015-Oct-17 14:46:49]: starting scheduler on jahromi-Sharif
  master input file  = /home/jahromi/Desktop/MyComputations/ALPS/Looper/parmlooper.in.xml
  master output file = /home/jahromi/Desktop/MyComputations/ALPS/Looper/parmlooper.out.xml
  termination file   = [disabled]
  total number of thread(s) = 1
  thread(s) per clone       = 1
  number of thread group(s) = 1
  auto evaluation = yes
  time limit = unlimited
  interval between checkpointing  = 3600 seconds
  interval between progress report = 600 seconds
  interval between vmusage report = infinity
  task range = all
  worker dump format = hdf5
  worker dump policy = running workers only
[2015-Oct-17 14:46:49]: task status: total number of tasks = 4
  new = 4, running = 0, continuing = 0, suspended = 0, finished = 0, completed = 0, skipped = 0
[2015-Oct-17 14:46:49]: starting 1 threadgroup(s)
[2015-Oct-17 14:46:49]: dispatching a new clone[1,1] on threadgroup[1]
(Jx+Jy) and (Jx-Jy) may not have opposite signs


FYI, I have enable the xyz bond support as instructed in this link and recompiled alps.

https://lists.phys.ethz.ch/pipermail/comp-phys-alps-users/2013/002282.html

I also tested the algorithm for the "XYZ spin" model available on the alps-looper source on wistaria GitHub and the results is the same and the problem exist there, either.

I would be so thankful if you could help me on this matter

Best

-- 
Saeed S. Jahromi
==========================================================
Postdoctoral Researcher

Physics Department, Sharif University of Technology
P.O. Box 11155-9161, Tehran , Iran.

Mailing Adrress: Azadi Ave., 14588-89694, Tehran, Iran

Homepage: http://www.saeedjahromi.com
==========================================================