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Thursday, March 08, 2012
10:00 AM - 11:30 AM
CNLS Conference Room (TA-3, Bldg 1690)

Seminar

Multiscale Atomistics for Defects in Electronic MaterialsIonic

Kaushik Dayal
Carnegie Mellon University in the Mechanics, Materials, and Computing Group of the Department of Civil and Environmental Engineering.

ferroelectrics and solid oxides. Defects in these materials play a central role in enabling their properties: for example, the electromechanics of ferroelectrics occurs by the nucleation and growth of domain wall defects, and solid oxide ionic conduction is through the motion of point defects. I will talk about our efforts to develop multiscale atomistic methods to understand the structure of defects in these materials. These materials have long-range electrostatic interactions between charges, as well as electric fieldsthat exist over all space outside the specimen. I will describe a multiscale methodology aimed at accurately and efficiently modeling defects in such materials in complex geometries. Our approach is based on a combination of Dirichlet-to-Neumann maps to consistently transform the problem from all-space to a finite domain; the quasicontinuum method to deal with short-range atomic interactions, and rigorous thermodynamic limits of dipole lattices from the literature. We apply the method to understand the electromechanics of a ferroelectric under complex electrical loading. The research is joint work with PhD student Jason Marshall, whose work received the 2011 USNCCM Best Poster Award for "Multiscale Mechanics with Long-Range Electrostatic Interactions."

Host: Turab Lookman, T-4, txl@lanl.gov, 665-0419