Computational study on C-80 enclosing mixed trimetallic nitride clusters of the form GdxM3-xN (M = Sc, Sm, Lu)

Abstract

Metallofullerenes of composition GdxM3-xN@C-80 with 0 <= x <= 3 and M = Sc, Sm, Lu, were investigated with respect to their geometric, electronic, energetic, and magnetic properties by Density Functional Theory, using the generalized gradient approximation in combination with an on-site correlation approach. Equilibrium structures were identified for both the free GdxM3-xN (0 <= x <= 3, M = Sc, Sm, Lu) units and the composite of the trimetallic nitride core and the fullerene cage. Although the core clusters generally tend toward planarity upon encapsulation into C-80, some species containing Sm atoms show a reversal of this trend. The electronic interaction between the cage and the core is characterized by the formation of a covalent region between both components. This effect proves to be strongest in those cases where no core rotation has been detected by experiment. Ferromagnetic ordering is favored by the free trimetallic nitride clusters involving Gd and Sm constituents. For GdxM3_ N@C-80 (0 <= x <= 3 and M = Sc, Sm, Lu), the ferromagnetically and antiferromagnetically ordered isomers are seen to be near-degenerate. A slight preference for the former alternative is found for Sm3N@C-80 while complexes containing Gd tend toward the latter.