I want to check if the ground state returned by DMRG is identical to the valence bond ground state of the AKLT model
( https://en.wikipedia.org/wiki/AKLT_model ).
For this purpose, I need to project a pair of spin-1/2 particles on adjacent sites onto the spin-1 (or triplet) subspace using the projection operator as shown on the following link
where the symbols “+”, “0” and “−” label the standard spin-1 basis states.
I have been able to construct the first and last terms of this operator using the pre-built operator “Proj” discussed on the webpage http://itensor.org/docs.cgi?page=classes/siteset but I have not been able to construct the second term (the one with |0>). Could you please help me? Thanks in advance.