Encapsulation of small magnetic clusters in fullerene cages: A density functional theory investigation within van der Waals corrections

Polina Tereshchuk, Juarez L.F. Da Silva*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The encapsulation of magnetic transition-metal (TM) clusters inside carbon cages (fullerenes, nanotubes) has been of great interest due to the wide range of applications, which spread from medical sensors in magnetic resonance imaging to photonic crystals. Several theoretical studies have been reported; however, our atomistic understanding of the physical properties of encapsulated magnetic TM 3d clusters is far from satisfactory. In this work, we will report general trends, derived from density functional theory within the generalized gradient approximation proposed by Perdew, Burke, and Ernzerhof (PBE), for the encapsulation properties of the TM m@C n (TM = Fe, Co, Ni; m=2-6, n=60,70,80,90) systems. Furthermore, to understand the role of the van der Waals corrections to the physical properties, we employed the empirical Grimme's correction (PBE+D2). We found that both PBE and PBE+D2 functionals yield almost the same geometric parameters, magnetic and electronic properties, however, PBE+D2 strongly enhances the encapsulation energy. We found that the center of mass of the TM m clusters is displaced towards the inside C n surfaces, except for large TM m clusters (m=5 and 6). For few cases, e.g., Co 4 and Fe 4, the encapsulation changes the putative lowest-energy structure compared to the isolated TM m clusters. We identified few physical parameters that play an important role in the sign and magnitude of the encapsulation energy, namely, cluster size, fullerene equatorial diameter, shape, curvature of the inside C n surface, number of TM atoms that bind directly to the inside C n surface, and the van der Waals correction. The total magnetic moment of encapsulated TM m clusters decreases compared with the isolated TM m clusters, which is expected due to the hybridization of the d-p states, and strongly depends on the size and shape of the fullerene cages.

Original languageEnglish
Article number195461
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number19
StatePublished - 29 May 2012
Externally publishedYes


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