Bulletin of the American Physical Society
Fall 2009 Meeting of the Four Corners Section of the APS
Volume 54, Number 14
Friday–Saturday, October 23–24, 2009; Golden, Colorado
Session A1: Opening/Plenary Session I |
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Chair: William Fairbank Jr., Colorado State University Room: Green Center Metals Hall |
Friday, October 23, 2009 12:30PM - 12:38PM |
A1.00001: Welcome Remarks Invited Speaker: |
Friday, October 23, 2009 12:38PM - 12:48PM |
A1.00002: Mines, Physics and the Energy Dilemma Invited Speaker: . [Preview Abstract] |
Friday, October 23, 2009 12:48PM - 1:24PM |
A1.00003: Environmental Impacts of a Shrinking Arctic Sea Ice Cover Invited Speaker: Arctic sea ice extent at the end of the summer melt season has declined sharply over the period of satellite observations and is projected to disappear entirely as concentrations of atmospheric greenhouse gases continue to rise. The extreme seasonal ice extent minima of September 2007 and 2008 serve as exclamation points on the downward trend and have fueled concern that rapid transition to a seasonally ice-free state may be imminent. While the factors forcing this trend have and will continue to be widely studied, less attention has been paid to the environmental impacts of current and future sea ice loss. Ice loss is already promoting increased wave action and coastal erosion and is resulting in strong rises in atmospheric temperature during autumn, not just at and near the surface, but extending through a considerable depth of the atmosphere. Through atmospheric transports, this strong warming, known as Arctic amplification, is starting to extend well beyond areas of ice loss, and will eventually influence Arctic land areas, glaciers, ice caps and the Greenland ice sheet. Though altering horizontal temperature gradients, continued loss of the ice cover is in turn likely to impact on patterns of atmospheric circulation and precipitation not just within the Arctic, but into middle latitudes. This talk addresses these and other emerging environmental impacts of Arctic sea ice loss. [Preview Abstract] |
Friday, October 23, 2009 1:24PM - 2:00PM |
A1.00004: Quantum-Mechanical Combinatorial Design of Solids with Target Properties Invited Speaker: One of the most striking aspects of solid-state physics is the diversity of structural forms in which crystals appear in Nature. The already rich repertoire of such (equilibrium) forms has recently been significantly enriched by the advent of artificial growth techniques (MBE, STM- atom positioning, etc) that can create desired structural forms, such as superlattices and geometric atomic clusters even in defiance of the rules of equilibrium thermodynamics. As is well known, different atomic configurations generally lead to different physical properties even at fixed chemical composition. While the most widely-known illustration of such ``form controls function'' rule is the dramatically different color, conductivity and hardness of the allotropical forms of pure carbon, the physics of semiconductor superstructures and nanostructures is full of striking examples of how optical, magnetic and transport properties depend sensitively on atomic configuration (e.g, compare the properties of random to ordered alloys). Yet, the history of material research generally proceeded via accidental discoveries of materials configuration with interesting physical property (semiconductivity, ferromagnetism; superconductivity etc). Given the ability of growing many different atomic configurations, and given the often sensitive dependence of physical properties on atomic configuration, makes one wonder: can one first articulate the desired target physical property, then search (within a class) for the configuration that has this property? This talk describes the recent steps made by solid-state theory and computational physics to address this ``Inverse Design'' problem. I will show how Genetic Algorithms, in combination with efficient (``Order N'') solutions to the Pseudopotential Schr\"odinger equation allow us to investigate astronomical spaces of atomic configurations in search of the structure with a target physical problem. Only a small fraction of all ($ \sim 10^{14}$ in our case) configurations need to be examined. Examples will include Band-Gap design in superlattices; architecture of impurity-clusters with desired optical properties, and Inverse Design of the Curie temperature in dilute magnetic systems. [Preview Abstract] |
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