Here is the patch. I'll add that to the next release.

--- mc/spins/spinmc_factory.C (revision 5665)
+++ mc/spins/spinmc_factory.C (working copy)
@@ -139,6 +139,8 @@
       produceError(parms);
       return 0;
     }
+  else if (parms["MODEL"]=="O(4)")
+    return new SpinSim<ONMoment<4>,MIdMatrix<double,4> >(where,parms,node);
   else if (parms["MODEL"]=="Heisenberg")
     switch (maxElemCount) {
       case 1:



On 14 Jul 2011, at 05:11, Rachele Nerattini wrote:

Dear Mr Troyer,

I've already written to you some months ago to ask you how could I perform a MC classical simulation of the O(4) model.
I've edited the file spinmc_factory.C as you suggested and typed make install to make it work.
The installation of every packages seemed to be ended well. So I prepared the input file with MODEL O(4) but It didn't  work.
It seemed as if the simulation started in the proper way but then it stopped with this error:

impossible to perform the simulation, impossible to find the O(4) model in the file
factory.C

What is this file? Where I can find it and how can I edit it?

Thank you for your help and sorry for my several requests of help.

Best Regards
Rachele Nerattini