The spins of multinuclear (transition metal) complexes are generally coupled together, which we call magnetic coupling. In many cases, a simple, phenomenological Hamiltonian operator, the Heisenberg-Dirac-van Vleck operator, is sufficient to model the energetics of the spin eigenstates. This Hamiltonian operator can be parameterized either by experimental methods or by high-precision quantum mechanical calculations.

However, there are still some open questions concerning the coupling mechanisms between the magnetic centers. Since the energetics resulting from these couplings can be correctly described with high-precision calculations, it should be possible to determine crucial information about the individual couplings directly from the associated wave function.

In our work, we use the density matrix renormalization group to generate such wave functions and then analyze them with orbital entropy masses. In this way, we are able to trace coupling pathways and understand the effect of chemical modifications (e.g., protonations) on such complexes.

Publications

• C. J. Stein, D. A. Pantazis, V. Krewald, Orbital entanglement analysis of exchange-coupled systems, J. Phys. Chem. Lett., 10, 2019, 6762.