Spin Glass Server
This is a continuation of the Spin Glass service originally provided by the former COPhy research group of Frauke Liers and the former research group of Michael Jünger at the University of Cologne. With the permission of these and the further contributors Petra Mutzel, Giovanni Rinaldi, Angelika Wiegele, Martin Diehl, and Gerhard Reinelt, the service has been relaunched at the University of Bonn by Sven Mallach. We also gratefully acknowledge the work of Thomas Lange, Marc Egger, and Mark Sprenger.
This service computes exact ground states of Ising spin glasses and partition functions of Potts glasses with many states.
The following geometries are supported:
 Ising spin glass on a:
 twodimensional planar quadratic lattice (free boundary in at least one direction)
 complete graph (SherringtonKirkpatrick (SK) spinglass model). For the SK model, we use the Biq Mac algorithm.
 Dominant contribution in partition function for Potts glasses with many states (on all graph types).
Further, for the geometries
 twodimensional quadratic lattice on a torus (periodic boundaries in both directions)
 threedimensional lattice (periodic boundaries in all directions)
Please note that this service comes without any guarantee or warranty. The input format is described below, results are returned by email.
Submit your file(s) ...
(each instance has to be a text file; files can be bundled into an archive; supported archiveformats are tar, tar.gz and zip)
The input format is as follows:
name: the name of the instance
spin_i1 spin_j1 coupling between i1 and j1
spin_i2 spin_j2 coupling between i2 and j2
...
If the instance should be named like the filename, simply skip the line
name: ...
in the file.Lattices with uniformly distributed ±J couplings need to be scaled to ±1 couplings.
See an example of the input format together with the corresponding results from the server here.
For lattice models, spins are numbered sequentially layer by layer starting with index 1.
For example, a twodimensional 3x3 spin glass is numbered as follows:



(1)(2)(3)
  
(4)(5)(6)
  
(7)(8)(9)
  
For the nonlattice models such as the SherringtonKirkpatrick (SK) model, the order of the spins is arbitrary.(1)(2)(3)
  
(4)(5)(6)
  
(7)(8)(9)
  
A more general instance generator can be downloaded here.