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|
|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
|Date:||10 / 21 / 2013|
|Time:||02:30pm - 03:30pm|