Electro-Optical Properties and Structural Stability Perspectives of M 3 N and M 2 C 2 (M = Sc, La) Clusters Encapsulated in B 80 Fullerene: A Density Functional Theory Study ZABIOLLAH MAHDAVIFAR, 1,2,3 MINA ERSHADIFAR, 1 and ABDOLHADI FARROKHNIA 1 1.—Department of Chemistry, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran. 2.—e-mail: z_mahdavifar@scu.ac.ir. 3.—e-mail: zb_nojini@scu.ac.ir In this work, the stability of metal nitride/carbide cluster borofullerenes, namely M 3 N@B 80 /M 2 C 2 @B 80 , by means of density functional theory (DFT) were evaluated. Detailed studies on M 3 N@B 80 /M 2 C 2 @B 80 (M = Sc, La) series indicate that these structures have high thermodynamic and kinetic stability due to the large value of calculated embedding energies and highest occupied molecular orbital-lowest unoccupied molecular orbital (H-L) energy gaps which indicate that the Sc 3 N, Sc 2 C 2 , La 3 N and La 2 C 2 clusters can form viable stable complexes with B 80 fullerene. Our computations show the Sc 3 N@B 80 borofullerene has the highest thermodynamic and kinetic stability and the obtained trend for ther- modynamic stability is Sc 3 N@B 80 > Sc 2 C 2 @B 80 > La 2 C 2 @B 80 > La 3 N@B 80 . This trend is nearly the same as obtained for the kinetic stability trend; Sc 3 N@B 80 > Sc 2 C 2 @B 80 > La 3 N@B 80 > La 2 C 2 @B 80 . The H-L energy gap of Sc 3 N@B 80 and Sc 2 C 2 @B 80 are 1.45 eV and 1.39 eV respectively, much larger than La 3 @B 80 (1.18 eV) and La 2 C 2 @B 80 (1.13 eV), conﬁrming that the nitride and carbide cluster borofullerenes have relatively high kinetic stability and could be isolated experimentally. Also, substitution of Sc with La metal in the nitride and carbide clusters imposes a noticeable inﬂuence on the stability and electronic properties of M 3 N@B 80 /M 2 C 2 @B 80 structures. Analyses of electronic structure and nearest distance between clusters and fullerene reveal that both covalent and ionic interactions coexist between cluster and boron atoms. Especially in the case of La 2 C 2 @B 80 , the plausible electron conﬁguration of it is [(La 2 C 2 ) 2 @B 80 2+ ]. Additionally, the simulated adsorption spectra considered by means of time-dependent DFT calculations as well as circular dichroism spectra show some different absorption bands in a broad region, which is helpful to further experimental characterization. These results can promise some valuable assistance for the experimental synthesis of M 3 N/M 2 C 2 @B 80 struc- tures because of high thermodynamic and kinetic stability. Key words: Metal nitride/carbide cluster, encapsulation, boron fullerene, optoelectronic properties, TD-DFT INTRODUCTION The ability of fullerenes to encapsulate metal atoms was discovered for the ﬁrst time by Heath et al. 1 using mass spectrometric analysis. In 1991, the La@C 82 endohedral metallofullerene (EMF) was successfully synthesized and separated. 2 On the other hand, Stevenson et al. 3 reported a novel stable nitride clusterfullerene in 1999. The Sc 3 N@C 80 nitride clusterfullerene was formed by a Kratschmer–Huffman by using an electric arc (Received July 7, 2017; accepted September 13, 2017) Journal of ELECTRONIC MATERIALS DOI: 10.1007/s11664-017-5813-1 Ó 2017 The Minerals, Metals & Materials Society