Modeling and Atomistic Simulations of Nanowires – Fabrication and Mechanics

 
Modeling and simulations play key roles in modern science and engineering.  While modeling and simulation can help interpret experimental observations,  we here focus on their functions in discoveries and predictions. This talk  starts with the discoveries of a novel diffusion process on surfaces and a  corresponding characteristic length scale during fabrication. The  discoveries have led to the understanding why nanorods (or shorter nanowires)　are nano in dimension. For decades, it has remained unknown why nanorods  are nano, although their fabrication is common on almost all campuses of  research universities. Going beyond merely scientific discoveries, we have  integrated the discoveries and literature knowledge to design the  fabrication of nanowires. The design predicts a self-assembly of nanowires  bifurcation. Subsequent experiments have validated the prediction. The  discoveries and predictions also extend to mechanical deformation of  nanowires – including nanoelasticity and nanoplasticity. Atomistic  simulations reveal that elastic stiffening or softening is primarily the  result of competition between electron redistribution and bond loss near  surfaces; nonlinear elasticity also contributes to the competition. As  deformation transitions from elastic to plastic regime, new mechanisms of  twin-dislocation interactions can make nanowires stronger.　 

Bibliography:
Hanchen Huang, Insight: Multiscale Modeling and Simulation, in Sandia  Technology, Fall Issue of 2007; pp 8-9, and cover page on the back.
L. G. Zhou and Hanchen Huang, “A Characteristic Length Scale of Nanorods  Diameter during Growth”, Physical Review Letters 101, 266102-1-4 (2008); 
featured in DoE Office of Science weekly report with the title “Surface  Science Breakthrough: Reason for Nanorod Growth Discovered”
S. J. Liu, Hanchen Huang, and C. H. Woo, “Schwoebel-Ehrlich Barrier: From  Two to Three Dimensions”, Applied Physics Letters 80, 3295-3297 (2002); 
Highlighted in the News Section of Nature on June 27, 2002
Bio:

Hanchen Huang holds a School of Engineering Named Professorship in  Sustainable Energy at the University of Connecticut (UConn); is a recipient 
of the Royal Society of London KTP Visiting Professorship in 2010; and is an  elected member of Connecticut Academy of Science and Engineering. His 
research focuses on atomistic simulations of nanofabrication and  nanomechanics, and this focus is augmented by experiments of nanofabrication.
 He has delivered more than 80 keynote/invited talks and seminars, and is an  associate editor of Journal of Engineering Materials and Technology.