So I've been trying to use this function: expHermitian(ITensor H, Cplx tau = 1)
but the operator that I want to exponentiate is the total Sz. Here is the code that I have so far:
auto ampo2 = AutoMPO(sites);
for(auto k : range1(Nspins))
ampo2 += "Sz",k;
auto proj = toMPO(ampo2);
auto exp2H = expHermitian(proj,2);
but I get an error that the function expects an ITensor object as the first argument (as expected). Is it possible to somehow do what I am trying to do?