MD Simulation of Structural and Mechanical Transformation of Single-Walled Carbon Nanotubes Under Pressure

Abstract. We investigate the structural and mechanical properties of single-walled carbon nanotubes (SWNTs) under hydrostatic pressure, using constant-pressuremolec-ular dynamics (MD) simulations. We observed that all the SWNTs, independent of their size and chirality, behave like a classical elastic ring exhibiting a buckling transi-tion transforming their cross-sectional shape from a circle to an ellipse. The simulated critical transition pressure agrees well with the prediction from continuum mechanics theory, even for the smallest SWNT with a radius of 0.4nm. Accompanying the buck-ling shape transition, there is a mechanical hardness transition, upon which the radial moduli of the SWNTs decrease by two orders of magnitude. Further increase of pres-sure will eventually lead to a second transition from an elliptical to a peanut shape. The ratio of the second shape transition pressure over the first one is found to be very close to a constant of ∼1.2, independent of the tube size and chirality. PACS (2006): 81.07.De, 73.63.Fg, 85.35.Kt Key words: Carbon nanotube, high-pressure solid-state phase transformation, MD simulation