Fig. 2. (a) MO diagram displaying the eigenbasis and site basis of the frontier orbitals of FP3 in the N state. Since the sum of the site orbitals yields the MO that is lower in energy the tunnel coupling, t, is negative. (b) Visualization of the Hubbard terms for FP3, U and V are potential energy terms due to on-site and inter-site repulsion, and t is the kinetic energy term accounting for hopping between localized sites.
