A systematic study of rare gas atoms encapsulated in small fullerenes using dispersion corrected density functional theory

Abstract

The most stable fullerene structures from C20 to C60 are chosen to study the energetics and geometrical consequences of encapsulating the rare gas elements He, Ne, or Ar inside the fullerene cage using dispersion corrected density functional theory. An exponential increase in stability is found with increasing number of carbon atoms. A similar exponential law is found for the volume expansion of the cage due to rare gas encapsulation with decreasing number of carbon atoms. We show that dispersion interactions become important with increasing size of the fullerene cage, where Van der Waals forces between the rare gas atom and the fullerene cage start to dominate over repulsive interactions. The smallest fullerenes where encapsulation of a rare gas element is energetically still favorable are He@C48, Ne@C52, and Ar@C58. While dispersion interactions follow the trend Ar > Ne > He inside C60 due to the trend in the rare gas dipole polarizabilities, repulsive forces become soon dominant with smaller cage size and we have a complete reversal for the energetics of rare gas encapsulation at C50.

From small fullerenes to the graphene limit: A harmonic force‐field method for fullerenes and a comparison to density functional calculations for Goldberg–Coxeter fullerenes up to C980

“…Here, we only give the ideal point group of the graph, which is reproduced by the force field, even though a DFT geometry optimization may reduce the symmetry due to Jahn–Teller distortions (see for example the discussion in Refs. ). The rms deviations listed for the bond lengths, bond angles, and torsion angles show that the EHFF performs well, especially if we consider that the bond lengths have been fixed to experimental values (note that the rms error for the bond distances can be considerably reduced if we use distances closer to the PBE optimized structure).…”

“…We chose the most stable fullerene structures for each vertex number up to C 60 (see Ref. for details), plus some selected fullerenes up to C 100 . As candidates for larger fullerenes beyond 100 vertices, we chose the Goldberg–Coxeter transforms of C 20 , that is, GC k , l [C 20 ‐ I h ] = C N with .…”

“…All structures were treated as closed‐shell singlet molecules, except for some of the smaller fullerenes as detailed in Ref. .…”

On the directional character of orbital compression: A model study of the electric properties of LiH–(He) complexes

“…Of significant importance are also some experimental and theoretical studies demonstrating that solvation of atoms and molecules in helium or superfluid helium nanodroplets may reveal many subtle details of their electronic structure as well as spectroscopic properties [49][50][51][52][53]. Besides the fact that the helium atom proved to be a highly valuable molecular object to model the effect of orbital compression, much attention has been also devoted to understand the impact of external spatial confinement and plasma environments on its electronic structure and fundamental properties [54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72]. Particularly, it has been demonstrated that polarizability (α) and second hyperpolarizability (γ) of the spatially restricted He atom is significantly reduced in comparison to the free atom [56,57,[61][62][63][64].…”

A Noncovalent Binding Strategy to Capture Noble Gases, Hydrogen and Nitrogen

“…Encapsulation of charged or neutral molecules and noble gases in the inner cavities of organic host molecules is a fascinating area of research and various theoretical and experimental efforts exploring the viability of cage like molecules having endohedrally trapped noble gas atoms have been reported . Clathrates and hydrates are the earlier noble gas compounds known where the noble gas atoms are caged in cavities in the crystal lattice of the host compound formed by a network of hydrogen bonds between covalently bound molecules .…”