[ALPS-users] S^2 measurement

4 Mar 2013

      Dear all,

Is it possible to measure S^2 in ALPS ED for the Hubbard model?

I define S^2 in two different ways, one as 'pm'

<SITEOPERATOR name="pm" site="x">
   Splus(x)*Sminus(x)+Sz(x)*Sz(x)-Sz(x)
</SITEOPERATOR>

and another as 'mp'

<SITEOPERATOR name="mp" site="x">
   Sminus(x)*Splus(x)+Sz(x)*Sz(x)+Sz(x)
</SITEOPERATOR>

and measurements gives different results, though they should be the same.
At the moment, I cannot understand where is the problem.

Thanks for any comments,
Volodymyr Derzhko