Relaxation and Aging Processes out of Equilibrium

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). TECHNICAL SUMMARY This award supports theoretical research and education in systems far from equilibrium that evolve with slow dynamics. The PI aims to generalize a theoretical framework that he has proposed to systems that evolve according to a detailed balance violating dynamics and that therefore relax toward nonequilibrium steady states. The PI's framework is based on the notion of local scale invariance. Progress along these lines would enhance understanding of relaxation and aging at a fundamental level. Combining advanced analytical and numerical techniques, the PI will explore several novel aspects of relaxation and aging processes, including: 1. Aging and fluctuations in reaction-diffusion systems. Even though reversible chemical reactions are known to be characterized by slow dynamics, their aging regime has not yet been studied in detail. Building a predictive theory of aging would be highly desirable. Moreover, such processes are quite generic, occurring for any value of the system parameters. Thus, it should be relatively easy to set up experiments with real systems in order to verify the predictions from this theory. In addition, the proposed study of fluctuations in irreversible reaction-diffusion systems will yield new insights into the generic properties of truly out-of-equilibrium systems. 2. Aging in growth processes. The study of aging phenomena in growth processes began quite recently, and has addressed only linear Langevin equations. To describe processes beyond the validity of linear approximations, the PI proposes to investigate aging phenomena associated with nonlinear Langevin equations, as, e.g., the Kardar-Parisi-Zhang equation. 3. A novel approach for the description of aging systems. A recently uncovered mapping between nonequilibrium physics problems and string theoretical problems opens a novel and uncharted approach that the PI proposes to explore. This approach, together with anticipated generalizations of the PI's successful theory of local scale invariance, offers the exciting possibility of a unifying theoretical framework for the description of wide classes of aging systems. Training through research is the central educational aspect of the present proposal. The project allows both undergraduate and graduate students can contribute in a substantial and meaningful way. The students will have ample opportunities to become proficient in various analytical and numerical techniques, including parallel computing on state-of-the-art high performance computers. NONTECHNICAL SUMMARY This award supports theoretical research and education broadly on many-particle systems that in states far from equilibrium. Nonequilibrium systems and processes are ubiquitous and encompass a wide range of phenomena from materials growth to chemical systems that exhibit interesting spatial patterns to the processes that sustain life. The PI aims to advance our understanding of systems that are out of equilibrium by developing a theoretical approach to describe how a system in a nonequilbrium state transforms to a nonequilbrium state, as opposed to an equilibrium state, with time. This will contribute to our understanding of relaxation and aging processes that occur in materials, such as glasses, as well as chemical and other systems. Training through research is the central educational aspect of the present proposal. The project allows both undergraduate and graduate students can contribute in a substantial and meaningful way. The students will have ample opportunities to become proficient in various analytical and numerical techniques, including parallel computing on state-of-the-art high performance computers.