Evaluation of the elastic constants of nanoparticles from atomistic simulations

We present an approach to estimate the elastic constants of molecules and n anoparticles, based on the analysis of thermal fluctuations from Monte Carl o (MC) or molecular-dynamics (MD) atomistic simulations. The method and the force-field used for these calculations have been tested by the calculatio n of Young's modulus of a graphite sample along the basal plane; the calcul ated value was found to be 1.07 TPa, in very good agreement with the experi mentally determined one of 1.02 TPa. The results on a carbon-based nanotube indicate that for the longitudinal d irection of the particle, the value of the elastic constant is on the order of 400 GPa. The elastic constant of the considered nanotube in the radial direction is significantly lower, the predicted values being in the range 4 -7 GPa. The method was also applied to the elastic constants of a type of siloxane- based nanostructure, whose longitudinal elastic constant (30 GPa) is an ord er of magnitude lower than the corresponding value for the carbon-based nan otube. (C) 2001 Elsevier Science Ltd. All rights reserved.