Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MM: Fachverband Metall- und Materialphysik

MM 2: Computational Materials Modelling I - Multiscale: Fundamentals

MM 2.2: Vortrag

Montag, 26. März 2012, 10:30–10:45, TC 006

Atomistic and continuum regions: Effects of coupling — •Frohmut Rösch and Hans-Rainer Trebin — Universität Stuttgart, Institut für Theoretische und Angewandte Physik, 70550 Stuttgart

Molecular dynamics simulations are a standard technique in computational materials modelling. The size of investigated solid structures, however, is limited to about the micrometer length scale. Finite element methods are less restricted in this respect but lack the atomistic description of matter. Obviously, this leads to the idea to couple both methods. The region of interest then is treated in an atomistic fashion and connected to a linear elastic continuum outside.

In this talk, fundamental effects are presented that arise in dynamic multiscale hybrid simulations due to the interface region. The scheme and procedures are illustrated, which are required to connect the two methods. In a simple setup aluminium has been chosen as a test case. In the numerical experiments, one domain determines the displacement boundary conditions for the other. The results show that the corresponding fixed boundaries influence relaxation. The decomposition into two parts also leads to a sort of asynchronism in time. In the case of strong excitations, it is observed that the anharmonic contributions lead to a deviation from linear elasticity, which is used in the continuum. Furthermore, depending on the spatial resolution of the FE mesh, short-wavelength phonons are reflected backwards into the atomistic domain.