Dear João,

For easy-plane models, "Generalized Spin Correlations" is indeed the Green function. For isotropic Hamiltonians, these two and "Spin Correlations", which is diagonal Sz-Sz correlations, are also identical. For easy-axis case, it is not very easy to measure the Green function in the loop algorithm, and it is not implemented.

I hope that the explanation on the generalized susceptibilities in alps/looper documentation (http://todo.ap.t.u-tokyo.ac.jp/projects/alps-looper) is also helpful for you.

Best, Synge

On 2009/07/07, at 5:08, João Manuel Viana Parente Lopes wrote:

Dear Alps list,

Greatings from Angola...

I am trying to extract the Green Function and the local magnetization running the loop code. I tried into the simplest example..

param file:

LATTICE="open chain lattice" MODEL="spin" local_S=1/2 L=10 J=1 INITIAL_SITE=1 THERMALIZATION=15000 SWEEPS=150000 REPRESENTATION="SSE" MEASURE[Green Function]=true MEASURE[Correlations]=true MEASURE[Local Susceptibility]=true {T=0.05;}

the simulation runs in 1m but there is no output for either Green's Funtion or Local Magnetization... Am I doing something terrible wrong or the looper code is not given these measures?

Thanks in Advance João