A DFT Study of Single-Molecule Magnets (Mn₃ Dimers)

Single-molecule magnets (SMMs) have become of increasing interest for magnetic technology. This is due to their many quantum phenomena and the ability to modify their structure and magnetic properties. It is thus important that SMM properties be characterized; thus, two configurations of the Mn₃ dimer ferromagnetic (FM) and antiferromagnetic (AFM) have been studied via Density Functional Theory (DFT). Our calculations for the total spin of the FM (S = 12) and AFM (S = 0) configurations of the isolated dimers, agrees with the experimental spin results per monomer (S = 6)¹ only when the dimers are charged (+2) (similar to molecules in solvent). This charge issue brings about long range jellium effects which have to be corrected in DFT. Our results shed insight into the differences between the magnetic anisotropy, magnetic coupling constants and the spin for both the neutral and the charged (+2) versions of the FM and AFM dimer as a comparison. The application of the Makov-Payne method, for charge corrections, results in very small changes to the magnetic anisotropy and the magnetic coupling constants for both charged version of the Mn₃ dimers.
¹ Nguyen et al. J. Am. Chem. Soc. 2015, 137, 7160−7168.