I re-read your machine learning article on a Tree Tensor Network application, and I just want to make sure I know how to implement the steps.
At the first step of the procedure, we produce a 2-site reduced density matrix.
Question: As usual, do we move the orthogonality center into one of these sites before making the reduced density matrix?
We then move to a new pair of sites, we move the orthogonality center before generating isometries for each pair of sites.
Question: Is this correct?
After generating all the isometries, we contract them with the original MPS to produce a lower-rank MPS. Where is the orthogonality center during this stage -- is it moved to each MPS pair before contraction?
My misunderstanding seems rooted in misunderstanding the DMRG procedure (and the role of the orthogonality center) so I'll review that, however, I probably still need your help to understand it completely. I noticed that your machine learning paper doesn't discuss the orthogonality center at all, so either the paper is too short to include all of the details, or it isn't necessary in that application -- correct?