Hi, my 3-site Hamiltonian looks very easy. It's only 3 operators of spin-1/2. I set N=24 and no conserve_qns. However I add a periodic boundary condition. After the

for j=1:N-2

s1 = s[j]

s2 = s[j+1]

s3 = s[j+2]

hj = op("xx",s1) * op("xx",s2) * op("xx",s3)

Gj = exp(-1.0im * tau/2 * hj)

push!(gates,Gj)

end

I added

#periodic

s1 = s[N-1]

s2 = s[N]

s3 = s[1]

hj = op("xx",s1) * op("xx",s2) * op("xx",s3)

Gj = exp(-1.0im * tau/2 * hj)

push!(gates,Gj)

s1 = s[N]

s2 = s[1]

s3 = s[2]

hj = op("xx",s1) * op("xx",s2) * op("xx",s3)

Gj = exp(-1.0im * tau/2 * hj)

push!(gates,Gj)

#periodic finish

I need the PBC, but I can't make sure that is right.

If I add the number of sites, like 36, the time will be about 3 times as N=24.