PSU Mark
Eberly College of Science Mathematics Department

Meeting Details

For more information about this meeting, contact Fei Wang, Hope Shaffer, Toan Nguyen, Mark Levi, Victor Nistor, Jinchao Xu, Ludmil Zikatanov.

Title:Bridging time and length scales in atomistic simulations using hyper-QC
Seminar:Computational and Applied Mathematics Colloquium
Speaker:Ellad Tadmor, University of Minnesota
Abstract Link:http://www.aem.umn.edu/people/faculty/bio/tadmor.shtml
Abstract:
The quasicontinuum (QC) method is a spatial multiscale method that extends the length scales accessible to fully-atomistic simulations (like molecular dynamics (MD)) by several orders of magnitude. While the recent development of the so-called "hot-QC method" enables dynamic simulations at finite temperature, the times accessible to these simulations remain limited to the sub-microsecond time scale due to the small time step required for stability of the numerical integration. To address this limitation, we develop a novel finite-temperature QC method that can treat much longer time scales by coupling the hot-QC method with hyperdynamics - a method for accelerating time in MD simulations. We refer to the new approach as "hyper-QC". As in the original hyperdynamics method, hyper-QC is targeted at dynamical systems that exhibit a separation of time scales between short atomic vibration periods and long waiting times in metastable states. Acceleration is achieved by modifying the hot-QC potential energy to reduce the energy barriers between metastable states in a manner that ensures that the characteristic dynamics of the system are preserved. The methodology is validated by comparing hyper-QC results with those of full MD for 1D and 2D example problems. An interesting observation regarding to the entropic nature of dislocations, uncovered in a hyper-QC simulation, will also be discussed.

Room Reservation Information

Room Number:MB106
Date:10 / 21 / 2013
Time:02:30pm - 03:30pm