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Quantum chemical molecular dynamics simulations based on the density-functional tight-binding (DFTB) method were performed to investigate the role of oxygen in single-walled carbon nanotube (SWCNT) growth process. We found that a suitable content of oxygen in an iron nano-catalyst particle can reduce the internal thermal mobility of Fe atoms in catalyst due to the formation of strong FeO bonds. These...
A theoretical study of pentagon/hexagon-bearing isomers of the C32 and C86 fullerenes suggests that the diversity in electronic structure and vibrational properties is determined by the surface curvature of the fullerene cage rather than by the global bond network topology. The latter plays a greater role in small, highly constrained fullerene cages, while it can be safely ignored in the case of larger...
Nonequilibrium quantum chemical molecular dynamics (QM/MDs) simulation of early stages in the nucleation process of carbon nanotubes from acetylene feedstock on an Fe38 cluster was performed based on the density-functional tight-binding (DFTB) potential. Representative chemical reactions were studied by complimentary static DFTB and density functional theory (DFT) calculations. Oligomerization and...
Nonequilibrium high-temperature quantum chemical molecular dynamics simulations based on the self-consistent-charge density-functional tight-binding (DFTB) method for the conversion of C60 to SiC fullerene by way of periodic Si atom supply are presented. Random supply of Si atoms on the surface of a perfect Ih-C60 buckminsterfullerene without simultaneous carbon atom removal merely leads to formation...
Metal-catalyzed SWCNT growth has been modeled using quantum chemical molecular dynamics (QM/MD) in conjunction with feeding of carbon atoms to C 40 –Fe 55 and C 40 –Ni 55 model complexes at 1500K. The rate of Fe 55 -catalyzed SWCNT growth determined in this work was 19% slower than the Fe 38 -catalyzed growth rate. Conversely, Ni 55 -catalyzed...
The interaction of acetone with single wall carbon nanotubes (SWCNTs) was studied by temperature programmed desorption with mass spectrometry (TPD-MS), after reflux, sonication, or exposure to 7.6Torr of acetone vapors at room temperature. Acetone molecules adsorb strongly on SWCNTs desorbing at ∼400–900K, corresponding to desorption energies of ∼100–225kJ/mol, as intact molecules. Exchange of intact...
Iron-catalyzed SWCNT growth by carbon diffusion starting from a carbon cap has been demonstrated in density-functional tight-binding molecular dynamics simulations. A C 40 (5,5) SWCNT cap attached to an Fe 38 cluster was employed as initial model system. After 40 carbon atoms were supplied onto the iron surface for 20ps, dynamics were continued for 160ps without supply of further carbon...
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