Research Abstracts Online
January 2009 - March 2010
University of Minnesota Twin Cities
Institute of Technology
of Aerospace Engineering and Mechanics
PI: Ryan S. Elliott
Efficient Coupling of Ab Initio and Bifurcation Techniques for Structural Transformations in Transition-metal Materials
Structural transformations in transition-metal (TM) compounds are phenomena of extraordinary scientific and technological relevance. The properties of the earth’s interior, for example, are governed by phase transitions in Fe-bearing minerals at elevated pressures and temperatures. Temperature-, stress- and magnetic-field-controllable martensitic transformations in shape-memory-alloys (SMA) and other TM-bearing materials are the basis for technological applications of unquestionable interest (e.g., sensors and actuators). The possibility of employing these materials in nanoscale "smart” devices (e.g., drug-delivery systems) opens developments and applications of enormous potential. The study of these complex phenomena, still in its infancy, will require extensive and highly interdisciplinary research.
The use of quantum (ab initio) simulations is essential to model, characterize, and understand the behavior of these systems because they are controlled by phenomena involving electronic degrees of freedom (e.g., bond breaking and formation, orbital and charge ordering, etc.). With available numerical techniques, many phenomena in this class are a formidable challenge. Difficulties include: proper description of electronic correlation (TM compounds are usually correlated systems); modeling of realistic temperature and pressure conditions; and access to realistic time scales and size regimes. The goal of this project is to develop and interface different numerical techniques into a generalized approach that, based on accurate ab initio simulations, will exploit the efficiency of effective-potential models to perform extensive explorations of the phase space of these materials and to identify all possible kinetic pathways of transformations.
Dipta Bhanu Ghosh, Research Associate
Venkata Guthikonda, Graduate Student
Vincent Jusuf, Graduate Student
Dan S. Karls, Graduate Student