Molecular dynamics simulations of noble gases encapsulated in C₆₀Fullerene

Abstract

Molecular dynamics simulations of Helium (He), Neon (Ne), Argon (Ar), Krpton (Kr) and Xenon (Xe) encapsulated in C 60 are discussed, as well simulations of Fullerenes containing anywhere from two to four He atoms. Even for single atom encapsulates, no species resides at the geometric center of the Fullerene cage. Smaller atoms sit more off-center than larger ones, and He appears to be a special case in both centering and dynamics. Some encapsulated species stabilize the cage by stifling radial fluctuations and others disrupt it; adding Ne seems to have the most stabilizing effect, while Kr and Xe cause the largest radial atomic excursions. Multiple He encapsulates tend to stabilize the cage; such systems are very stressed and show structure over a wide temperature range. Based on dynamical information quadruple He seems to be close to the packing limit for C 60 .

Simulated structure and energetics of endohedral complexes of noble gas atoms in buckminsterfullerene

“…Our overall analysis of this somewhat ambiguous situation suggests that studies based on Lennard‐Jones potentials are more reliable than those on the other theoretical methods, leading to the conclusion that endohedral complex stability reaches a peak at the Ar complex, with most of the work in agreement that the Xe complex is energetically less stable than the uncomplexed species Xe+C 60 . The work by Even et al 8 did not report binding energies and is therefore not included in Table V. We do not agree with their analysis relating stability to the shape of the radial distribution function.…”

“…The present work has led to results that differ in various ways from the earlier studies. Looking first at those based on Lennard‐Jones interactions between the noble‐gas endoatom and the fullerene carbon atoms 3, 4, 8, we call attention to the fact that different studies used different Lennard‐Jones parameters. To see this clearly, we converted all the potentials to the form given in Eq.…”

“…Endohedral fullerene complexes have a growing number of applications in nanoscience and nanotechnology, and a variety of experimental methods have been implemented to synthesize endohedral complexes with noble gas atoms confined within a fullerene cage 1. These complexes have also been the subject of a number of theoretical investigations 2–8. However, the incomplete agreement among these results and their lack of consistency with the available experimental data indicate that a completely satisfactory description of the structure and energetics of these fullerene complexes had not yet emerged.…”

Mechanical and electronic properties of endofullerene Ne@C60studied via structure distortions

“…Nevertheless, they are very stable since the atom(s) cannot escape unless several bonds are broken. These molecules are generally selected as models of weak interaction systems [34][35][36]. The noble gas atom(s) can be put into the cage by heating the fullerenes in the presence of the gas at high temperatures and pressures [29][30][31][32][33] or by shooting them in as ions or metastable atoms [37,38].…”

“…NMR was employed to study the magnetic properties of 3 He@C 6À 60 and 3 He@C 6À 70 [41]. Lennard-Jones potential [42] and molecular dynamics simulations (MDS) [35] were used to predict the stabilities of exohedral XC 60 (X ¼ He, Ne, Ar, Kr and Xe) and endohedral X@C 60 complexes. The results show that some encapsulated species stabilized the cage and others disrupted it.…”