Place: ICAMS, Ruhr-Universität Bochum, Germany
In material simulations many different time and length scales are involved. To study macroscopic material properties based on a microscopic insight on the atomic level is one of the big challenges in theoretical material science. Including several orders of magnitude in time and length in one simulation and passing information back and forth between those in a consistent and accurate way would provide powerful tools for predictive materials modelling. When performing such simulations three main points need to be considered: How large does the system have to be for a realistic representation of the real system and to avoid finite size effects? How long does the simulation have to be to observe the behaviour of interest? And how accurate and transferable are the obtained results? The focus of this talk will be on the time scale problem in atomistic simulations. As the time step in regular molecular dynamics simulations is bound to the fastest motion in the system, which are usually the vibrations, the largest time step can only be in the order of femtoseconds. Several methods have been proposed to nevertheless cover the dynamical behaviour up to seconds or longer. A review of different approaches will be given and their advantages and limitations will be discussed.