The C₆₀ Formation Puzzle “Solved”:  QM/MD Simulations Reveal the Shrinking Hot Giant Road of the Dynamic Fullerene Self-Assembly Mechanism

Abstract

The dynamic self-assembly mechanism of fullerene molecules is an irreversible process emerging naturally under the nonequilibrium conditions of hot carbon vapor and is a consequence of the interplay between the dynamics and chemistry of polyyne chains, pi-conjugation and corresponding stabilization, and the dynamics of hot giant fullerene cages. In this feature article we briefly present an overview of experimental findings and past attempts to explain fullerene formation and show in detail how our recent quantum chemical molecular dynamics simulations of the dynamics of carbon vapor far from thermodynamic equilibrium have assisted in the discovery of the combined size-up/size-down "shrinking hot giant" road that leads to the formation of buckminsterfullerene C60, C70, and larger fullerenes. This formation mechanism is the first reported case of order created out of chaos where a distinct covalent bond network of an entire molecule is spontaneously self-assembled to a highly symmetric structure and fully explains the fullerene formation process consistently with all available experimental observations a priori. Experimental evidence suggests that it applies universally to all fullerene formation processes irrespective of the carbon source.

Ab initio calculation of carbon clusters. II. Relative stabilities of fullerene and nonfullerene C24

“…Indeed, the bowl-shaped isomer of C 20 has been experimentally detected in photoelectron spectroscopy ͑PES͒ experiment. 8,13 The experiment provides a supporting evidence for the growth mechanism [32][33][34][35][36][37] of the so-called "pentagon road" 32 by which the formation of fullerenes from small carbon fragment can be realized via incorporation of pentagons through annealing ͑ജ1473 K͒, consistent with the IPR. This growth mechanism can explain the high yield of C 60 production.…”

“…[28][29][30][31] Recently, a "shrinking hot giant road" which describes the self-assembled fullerene formation from chaotic hot carbon radicals under nonequilibrium conditions is proposed based on quantum mechanical molecular dynamics simulations within non-self-consisitent charge density functional tight binding approximation. 37 Starting from C 24 , previous theoretical calculations suggest that the classical fullerene cage is most likely the ground-state structure. 17,[22][23][24][25] An intermediate carbon phase, "cubic graphite" which has a simple cubic lattice formed by C 24 fullerene molecules and copolymerized by the square faces, has been characterized.…”

Milestones in molecular dynamics simulations of single-walled carbon nanotube formation: A brief critical review

“…Besides these grave deÀ ciencies, the standard REBO potential has À several other well-known problems. For example, in modeling gas-phase carbon densities it overestimates the sp 3 fraction compared to corresponding DFT simulations [40], while it underestimates the sp fraction [41] which is of paramount importance with respect to fullerene cage self-assembly [42]. Consequently, task 1a is never addressed in REBO-type MD simulations.…”

The Technology and Setup for High-Throughput Synthesis of Endohedral Metal Fullerenes

“…Isolation of individual EMF was carried out by high-performance liquid chromatography (HPLC). It should be noted that TiCl 4 Lewis acid is most effective and powerful in purification for the various types of pure metallofullerenes. Other Lewis acids (CuCl 2 , AlCl 3 ) did not demonstrate such results.…”

“…That clusters stabilized in shape and size through the loss of C 2 . This is described by "shrinking hot giant fullerene" concept [4].…”