Fig. 3: A molecular orbital graph indicating all possible tensor network bond indices between Nā=ā6 spin-orbital sites.

The solid lines denote the bond indices of a matrix product state as defined in Eq. (3). The restricted Hartree-Fock orbitals of the H\({}_{3}^{+}\) cation in the STO-3G basis set are provided as a minimal example of a closed-shell molecule with six spin-orbital sites.