Journal ArticleDOI
Quantum chemical molecular dynamics simulation of single-walled carbon nanotube cap nucleation on an iron particle.
Yasuhito Ohta,Yoshiko Okamoto,Alister J. Page,Stephan Irle,Stephan Irle,Keiji Morokuma,Keiji Morokuma +6 more
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TLDR
Computer simulation of metal-catalyzed SWNT nucleation on metal catalyst particles uses nonequilibrium density functional tight-binding molecular dynamics simulations and reports nucleation of sp(2)-carbon cap structures on an iron particle consisting of 38 atoms.Abstract:
The atomic scale details of single-walled carbon nanotube (SWNT) nucleation on metal catalyst particles are elusive to experimental observations. Computer simulation of metal-catalyzed SWNT nucleation is a challenging topic but potentially of great importance to understand the factors affecting SWNT diameters, chirality, and growth efficiency. In this work, we use nonequilibrium density functional tight-binding molecular dynamics simulations and report nucleation of sp(2)-carbon cap structures on an iron particle consisting of 38 atoms. One C(2) molecule was placed every 1.0 ps around an Fe(38) cluster for 30 ps, after which a further 410 ps of annealing simulation without carbon supply was performed. We find that sp(2)-carbon network nucleation and annealing processes occur in three sequential and repetitive stages: (A) polyyne chains on the metal surface react with each other to evolve into a Y-shaped polyyne junction, which preferentially form a five-membered ring as a nucleus; (B) polyyne chains on the first five-membered ring form an additional fused five- or six-membered ring; and (C) pentagon-to-hexagon self-healing rearrangement takes place with the help of short-lived polyyne chains, stabilized by the mobile metal atoms. The observed nucleation process resembles the formation of a fullerene cage. However, the metal particle plays a key role in differentiating the nucleation process from fullerene cage formation, most importantly by keeping the growing cap structure from closing into a fullerene cage and by keeping the carbon edge "alive" for the addition of new carbon material.read more
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Current understanding of the growth of carbon nanotubes in catalytic chemical vapour deposition
TL;DR: In the field of nanotube synthesis, catalytic chemical vapour deposition (CVD) is the prevailing synthesis method of carbon nanotubes as discussed by the authors, due to its higher degree of control and its scalability.
Journal ArticleDOI
Chirality Pure Carbon Nanotubes: Growth, Sorting, and Characterization.
TL;DR: It is the view that more efforts are still needed to develop both methodologies for preparing ultrapure SWCNTs in large quantity and nondestructive fast characterization techniques with high spatial resolution for various nanotube samples.
Journal ArticleDOI
The Phase of Iron Catalyst Nanoparticles during Carbon Nanotube Growth
C. T. Wirth,Bernhard C. Bayer,Andrew D. Gamalski,Santiago Esconjauregui,Robert S. Weatherup,Caterina Ducati,Carsten Baehtz,John Robertson,Stephan Hofmann +8 more
TL;DR: In this article, the authors study the Fe-catalyzed chemical vapor deposition of carbon nanotubes by complementary in situ grazing-incidence X-ray diffraction, in situ Xray reflectivity, and environmental transmission electron microscopy.
Journal ArticleDOI
Catalyzed Growth of Carbon Nanotube with Definable Chirality by Hybrid Molecular Dynamics−Force Biased Monte Carlo Simulations
TL;DR: A CNT with definable chirality is obtained, and a step-by-step atomistic description of the nucleation process is presented, and the importance of the relaxation of the network is highlighted by the observed healing of defects.
Journal ArticleDOI
Changing chirality during single-walled carbon nanotube growth : a reactive molecular dynamics/Monte Carlo study
TL;DR: It is clearly illustrated in the present study that during the growth process, the carbon network is continuously restructured by a metal-mediated process, thereby healing many topological defects.
References
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Journal ArticleDOI
Crystalline Ropes of Metallic Carbon Nanotubes
Andreas Thess,R. S. Lee,Pavel Nikolaev,Hongjie Dai,Pierre Petit,J. Robert,Chunhui Xu,Young Hee Lee,Seong-Gon Kim,Andrew G. Rinzler,Daniel T. Colbert,Gustavo E. Scuseria,David Tománek,John E. Fischer,Richard E. Smalley +14 more
TL;DR: X-ray diffraction and electron microscopy showed that fullerene single-wall nanotubes (SWNTs) are nearly uniform in diameter and that they self-organize into “ropes,” which consist of 100 to 500 SWNTs in a two-dimensional triangular lattice with a lattice constant of 17 angstroms.
Journal ArticleDOI
Nosé-Hoover chains : the canonical ensemble via continuous dynamics
TL;DR: In this paper, a modification of the Nose-Hoover dynamics is proposed which includes not a single thermostat variable but a chain of variables, Nose chains, which gives the canonical distribution where the simple formalism fails.
Journal ArticleDOI
Self-consistent-charge density-functional tight-binding method for simulations of complex materials properties
Marcus Elstner,Marcus Elstner,D. Porezag,G. Jungnickel,J. Elsner,M. Haugk,Th. Frauenheim,Sándor Suhai,Gotthard Seifert +8 more
TL;DR: In this paper, an extension of the tight-binding (TB) approach to improve total energies, forces, and transferability is presented. The method is based on a second-order expansion of the Kohn-Sham total energy in density-functional theory (DFT) with respect to charge density fluctuations.
Journal ArticleDOI
Construction of tight-binding-like potentials on the basis of density-functional theory: Application to carbon.
TL;DR: In this article, a density-functional-based scheme for determining the necessary parameters of common nonorthogonal tight-binding (TB) models within the framework of the linear-combination-of-atomic-orbitals formalism using the local density approximation (LDA).
Journal ArticleDOI
MacMolPlt: a graphical user interface for GAMESS.
Brett M. Bode,Mark S. Gordon +1 more
TL;DR: A description of MacMolPlt, a graphical user interface for the General Atomic and Molecular Electronic Structure System, GAMESS, is presented and the strategy for direct computation of orbital, total electron density, and molecular electrostatic potential surfaces is discussed.