Scanning tunneling microscope (STM), atomic force microscope (AFM) and related microscopes (SPM) have been demonstrated as tools for fabricating nanoscale structures - a top-down approach to Nanotechnology. However, this technology has severe limitations in terms of throughput and reproducibility during fabrication. In order to overcome the present day limitations in nanofabrication and the future problems with working nanomachines, it is imperative to understand the underlying atomistic phenomena associated with material modification at nanoscale. Molecular dynamics (MD) simulations, by virtue of their high temporal and spatial resolution, offer an ideal approach to gain insights into the atomic- scale processes and understand the mechanisms.
In this paper, we study the deformation of two substrates (polyethylene and silicon) during indentation by a rigid tip and present a new approach, based on a local strain diagnostic (Falk and Langer, 1998), to identify and characterize the structural rearrangements occuring during indentation. The mechanisms and dynamics of the processes involved are investigated by analyzing the changes in position, atomic binding energy, atomic stress tensor, and kinetic energy of the atoms in the deformed region.
Falk M. L., and Langer J. S., Phys. Rev. E, 57, 7192, (1998)
Surya K. Mallapragada
Department of Chemical Engineering, Iowa State University
1035, Sweeney Hall
Ames, Iowa 50011 USA