Kristen A. Fichthorn

  • Atomic-Scale Simulation of Rare-Event Kinetics: Addressing the Small-Barrier Problem

    Kristen A. Fichthorn
    The Pennsylvania State University, University Park, PA, USA

    A significant challenge in simulating kinetics in solids is dealing with the small-barrier problem, which occurs when groups of recurrent free-energy minima connected by small barriers are separated from the full phase space of the system by high barriers. These groups of states are called superbasins and they can considerably reduce the efficiency of the simulation. We have addressed this problem with both accelerated molecular dynamics (AMD) [1-3] and in kinetic Monte Carlo (KMC) simulations. In this talk, I will highlight our local superbasin KMC (LSKMC) method [4] for identifying local superbasins in KMC simulations containing both superbasins and non-superbasin events. I will demonstrate aspects of our AMD and LSKMC methods in several examples involving thin-film growth and dynamics at surfaces, which highlight the computational efficiency of these algorithms.

    [1] R. A. Miron and K. A. Fichthorn, “Accelerated molecular-dynamics of rare events with the bond-boost method”, J. Chem. Phys. 119, 6210 (2003).

    [2] R. A. Miron and K. A. Fichthorn, “Multiple-time scale accelerated molecular dynamics: Addressing the small-barrier problem”, Phys. Rev. Lett. 93, 128301 (2004).

    [3] Y. Lin and K. A. Fichthorn, “An accelerated molecular dynamics study of the GaAs(001) 2(2×4)/c(2×8) surface”, Phys. Rev. B 86, 165303 (2012).

    [4] K. A. Fichthorn and Y. Lin, “A local superbasin kinetic Monte Carlo method”, J. Chem. Phys. 138, 164104 (2013).