Electronic Transport, Structure, and Energetics of Endohedral Gd@C₈₂ Metallofullerenes

Abstract

Electronic structure and transport properties of the fullerene 82 and the metallofullerene Gd@82 are investigated with density functional theory and the Landauer-Buttiker formalism. The ground state structure of Gd@82 is found to have the Gd atom below the C-C bond on the C2 molecular axis of 82. Insertion of Gd into 82 deforms the carbon chain in the vicinity of the Gd atoms. Significant overlap of the electron distribution is found between Gd and the 82 cage, with the transferred Gd electron density localized mainly on the nearest carbon atoms. This charge localization reduces some of the conducting channels for the transport, causing a reduction in the conductivity of the Gd@82 species relative to the empty 82 molecule. The electron transport across the metallofullerene is found to be insensitive to the spin state of the Gd atom.

Structural and electronic properties of Gd@C60: All-electron relativistic total-energy study

“…The calculated distances between the La ion and the proximal C atoms are slightly larger with values of 2.55-2.64 Å [11] in La@C 60 . The calculated binding energy of Gd inside C 60 (3.77 eV) is significantly smaller than that of Gd inside C 82 (5.64 eV [5]), but larger than that of La inside C 60 (2.65 eV) [11].…”

“…The spin densities on the Gd ion and C 60 are 6.74 and −1.26, respectively; therefore the seven spins on the Gd ion and one spin on C 60 are antiferromagnetically coupled, similar to the case of Gd@C 82 [5]. The spin multiplicities of S = 5, 7, and 9 are 0.08, 0.10 and 0.67 eV higher in energy, respectively, than that of S = 7.…”

“…Gd@C 60 is the most abundantly produced species of Gd-based metallofullerenes in carbon arc process. Unlike soluble Gd@C 82 , which has been studied by extensive experiments and two theoretical works [4,5], the structural and electronic properties of insoluble Gd@C 60 are overlooked largely. Only Lu et al [6] have calculated the electronic structure of Gd@C 60 assuming that Gd is located on the center of C 60 and found that only two 6s electrons of Gd are ionized, leaving the 5d electron behind.…”

“…Addition of Gd slightly lengthens the proximal C-C double and single bonds by 0.04 and 0.02 Å, respectively. In Gd@C 82 [5] and La@C 60 [11], the Gd and La ions are positioned slightly away from the C-C double bond based on the density functional theory calculations with the effective core potential approximation. The calculated distances between the Gd ion and the proximal C atoms are 2.47 and 2.38-2.41 Å [5] in Gd@C 60 and Gd@C 82 , respectively.…”

“…In Gd@C 82 [5] and La@C 60 [11], the Gd and La ions are positioned slightly away from the C-C double bond based on the density functional theory calculations with the effective core potential approximation. The calculated distances between the Gd ion and the proximal C atoms are 2.47 and 2.38-2.41 Å [5] in Gd@C 60 and Gd@C 82 , respectively. The calculated distances between the La ion and the proximal C atoms are slightly larger with values of 2.55-2.64 Å [11] in La@C 60 .…”