Large Scale Nanocarbon Simulations
S. Tejima, M. Iizuka, N. Park, S. Berber, H. Nakamura and D. Tomanek
Research Organization for Information Science & Technology, JP
largescale simulation, carbonnanotube, mechanical properties
The mechanical response of carbon nanotubes to revere deformation has attracted much attention since their discovery in 1991. Carbon nanotubes have already demonstrated exceptional mechanical properties: their excellent flexibility during bending have been observed experimentally. Nanotubes combine high stiffness with elasticity and the ability to buckle and collapse in a reversible manner even largely axially compressed or twisted deformation. For these reasons, it has been suggested that carbon nanotubes could be promising candidates for a new generation of extremely light and super strong fiver. However, experiments probing the strength of nanotubes are very challenging, but to the difficulties in growing high quality, defect-free nanotubes of sufficient length and in measuring the strength of nanoscale objects. Theoretically, investigating the strength of carbon nanotubes requires modeling of inherently mesoscopic phenomena, such as plasticity and fracture on a microscopic compose of several thousands of atoms. The first principle methods based on the wave function of electrons are limited in the atomic structure of several hundreds atoms, but a large scale tight-binding simulation based on quantum orbit presents challenging up to tens of thousands of atoms. Our large scale simulation using Earth Simulator enables ourselves to reach this target. In simulations, elastic and buckling properties of nanotubes in difference radius and chirality are investigated on. When the change in length is small fracture under the compression, resisted load is proportional to compressed length. Above the first critical load, carbon nanotube occurs symmetrical buckling with keeping the elastic property. Above the second critical higher than first one, carbon nanotube dose asymmetrical buckling and into a fracture. The dependence of buckling point on length, radius and chirality of nanotubes will discuss in detail.
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Nanotech 2005 Conference Program Abstract