TeNPy Forum

I am a new member of TenPy. I have been trying to compute the istropic spin-spin correlation C(r) = \frac{1}{L}\sum_{i=1}^{L} (S^{x}_{i}S^{x}_{i+r}+S^{y}_{i}S^{y}_{i+r}+S^{z}_{i}S^{z}_{i+r}) using TenPy for the antiferromagnetic 1D J1-J2 model with PBC for L = 20 and check it against the exact diago...