Universität zu Köln - Institut für Informatik

Spin Glass Server
(This service is provided by COPhy and M. Jünger's group.)

This page offers a service to compute exact ground states of Ising spin glasses.
Instances can be uploaded using this web-interface or our command-line client (for Unix/Linux based OS). The results are returned by email.
We recommend to use the command-line client for the submission of many instances.

The following geometries are supported:

Ising spin glass on a:

two-dimensional planar quadratic lattice (free boundary in at least one direction)
two-dimensional quadratic lattice on a torus (periodic boundaries in both directions)
three-dimensional lattice (periodic boundaries in all directions)
complete graph (Sherrington-Kirkpatrick (SK) spin-glass model)

For the SK model, we use an algorithm provided to us by our colleagues G. Rinaldi, F. Rendl and A. Wiegele.

Submit your file(s) ...
(each instance has to be a text file; files can be bundled into an archive; supported archive-formats 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 two-dimensional 3x3 spin glass is numbered as follows:

     |       |       |
      -(1)---(2)---(3)--
     |       |       |
      -(4)---(5)---(6)--
     |       |       |
      -(7)---(8)---(9)--
     |       |       |

For the non-lattice models such as the Sherrington-Kirkpatrick (SK) model, the order of the spins is arbitrary.
If you have any special request or problems, please contact us directly: spinglass AT informatik.uni-koeln.de

... or use the sample generator:

number of samples:		Number of samples that shall be generated.
instance type:	gauss	Two-dimensional lattice on a torus with periodic boundaries. Couplings are chosen according to a Gaussian distribution around zero with standard deviation one, scaled by 10^5.
	pm	Two-dimensional lattice on a torus with periodic boundaries. Couplings are chosen according to a bimodal distribution, i.e. they take values +1 or -1 with equal probability.
	gauss3	Three-dimensional lattice with periodic boundaries. Couplings are chosen according to a Gaussian distribution around zero with standard deviation one, scaled by 10^5.
	pm3	Three-dimensional lattice with periodic boundaries. Couplings are chosen according to a bimodal distribution, i.e. they take values +1 or -1 with equal probability.
lattice size L:		Specification of an LxL lattice (or respectively LxLxL).
email address:		The results will be returned to this email address.

A more general instance generator can be downloaded here.