Development and Application of Fe³⁺, Al³⁺, Cr³⁺ Dummy Atom Models for Metal-Organic Frameworks

Various metal-organic frameworks (MOFs) containing trivalent cations (such as Fe³⁺, Al³⁺, and Cr³⁺) have been reported and have shown great potential in applications. However, the high structural diversity and strong electronic interactions between metal centers and their ligands make the molecular dynamics simulations of MOFs challenging. In this work, we developed new dummy atom models for Fe³⁺, Al³⁺, and Cr³⁺ cations, which can be used in classical molecular dynamics simulations of MOFs. In our models, the correct solvation free energies and metal-ligand distances can be simultaneously reproduced. Furthermore, the usefulness and transferability of our models were validated using the commonly studied MIL-100(M) (M = Fe³⁺, Al³⁺, Cr³⁺) and MIL-88B(Fe³⁺) systems. Our developed models offer a valuable tool for simulating complex systems containing Fe³⁺, Al³⁺, and Cr³⁺ cations with octahedral coordination structures.