Computational materials chemistry at the nanoscale

Tahir Çagin, Jianwei Che, Yue Qi, Yanhua Zhou, Ersan Demiralp, Guanghua Gao, and William A. Goddard
Materials and Process Simulation Center, Beckman Institute (139-74), Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125

In order to illustracte how atomistic modeling is being used to determine the structure, physical, and chemical properties of materials at the nanoscale, we present here the results of molecular dynamics(MD) simulations on nanoscale assemblies of such materials as carbon nanotubes, diamond surface, metal alloy nanowires, and ceramics. We also include here the results of nonequilibrium MD simulations on the nanorheology of a monolayer of wear inhibitor self-assembled on two metal oxide surface, separated by hexadecane lubricant, and subject to steady state shear.

We also present recent developments in force fields(FF) required to describe bond breaking and phase transformations in such systems. We apply these to study of plasticity in metal alloy nanowires where we find that depending on the strain rate, the wire may deform plastically (forming twins), neck and fracture, or transition to amorphous phase.

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