The IFN Computational Nanoscience Group
Digging out the hidden order in metallic liquids and glasses
C. Z. Wang Ames Laboratory-US Department of Energy and Department of Physics, Iowa State University, Ames Iowa 50011
Friday, December 3 2010 at 1:30 PM
Resource Center for Science and Engineering
Room 344
Rio Piedras Campus
University of Puerto Rico
Abstract:
Although metallic liquids and glasses look quite homogenous macroscopically, most of them exhibit structural and chemical orders at the atomic scale. This short-range (SRO) or medium-range order (MRO) occurs on a length scale of 5-20 Å. However, they are generally difficult to discern at the macroscopic scale due to random orientations of the ordered units. Recently, we develop an efficient computational algorithm to align the neighborhood cluster around each atom to reveal the hidden symmetry and order contained in the system. In our alignment algorithm, we put the center atoms into a common origin and rigidly rotate the clusters to maximize their common registry to reveal any existing SRO or MRO. The results determine what are the major competing orders and the strengths of various orders in the system. Such atomic scale information are very difficult to acquire by experiments and are critical for understanding the mechanism of glass formation and phase selection, and nucleation during the rapid solidification from the metallic liquids.
About the speaker:
Dr. Wang is an expert on atomistic modeling and simulation study of structural, dynamical and electronic properties as well as phase transformation of condensed matter systems and molecules. He is also a leading scientist on developing computational methods for material modeling, mainly on developing transferable tight-binding parameters and also molecular dynamics. He is now leading the CMSN project: Condensed Matter Theory, Particle-Solid Interactions, and Engineering Physics in the DOE Ames Laboratory. The two tasks included in his CMSN project are: 1) Solar energy conversion for photovoltaic applications and 2) Novel nanomaterials for energy storage.
