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