Structure of Polynitrogen Clusters Encapsulated in C₆₀: A Density Functional Study

Abstract

Using density functional theory, we explore the possibility of trapping polynitrogen clusters inside C 60 fullerene cages. We found that a maximum of 13 nitrogen atoms can be encapsulated in a C 60 cage without distorting the C 60 cage significantly. The nitrogen clusters in confinement exhibit unique stable structures in polymeric form, mostly in single- and double-bonded formations. The N n @C 60 molecules retain their structure, even at 300 K, for n ≤ 12. The Mulliken charge analysis shows a very small charge transfer in N@C 60, consistent with the quartet spin state of N. However, for 2 < n < 10, charge transfer takes place from the cage surface to the N n compounds, and inverse polarization thereafter.