I can not figured out what are the susceptibility units in the results of calculations. In tutorial ed-06 on V15 cluster (and also results of QMC that match perfectly) for T/J=10 I would expect \chi*T as for fully decoupled 15 spins 1/2 that is S(S+1)/3 eq 0.25. There is instead 0.2375133. Where is the problem? Best wishes Tadeusz