Institutional research of nanoelectromagnetics

Philippe LAMBIN

University of Namur, Belgium
Elasticity at the nanoscopic scale

The discovery of fullerenes, nanotubes and other nanoscopic forms of carbon has contributed a lot to the evolution of nanosciences, while stimulating further the development of nanotechnology. Many phenomena taking place at this length scale are hidden and sometimes forbidden at the microscopic and macroscopic levels. Aside from new physic laws governed by quantum mechanics, some classical concepts may survive in the nanoworld. Elasticity is one domain of materials science that can reasonably be applied to nanostructures. Care should be taken, however, to maintain well-defined quantities. Not all the elastic constants keep up their meaning when transposed to the nanoscopic scale. For instance, Young modulus of about 5 TPa has been predicted for single-walled carbon nanotubes. The fact is that this modulus has no more significance at the atomic level. Other elastic properties, by contrast, can be defined unambiguously at the atomic level and, in principle, can be measured experimentally. That is important because mechanical properties of nanostructures can be predicted from elasticity if and only if reliable data exist. The task is not easy, which explains why available values, if any, may differ significantly from each other. Ab-initio calculations can be a substitute for experiment for providing the input data needed by classical mechanics.