ct6b00859_si_001.pdf (1 MB)
Generalized Temporal Acceleration Scheme for Kinetic Monte Carlo Simulations of Surface Catalytic Processes by Scaling the Rates of Fast Reactions
journal contribution
posted on 2017-02-14, 00:00 authored by Eric C. Dybeck, Craig P. Plaisance, Matthew NeurockA novel
algorithm is presented that achieves temporal acceleration
during kinetic Monte Carlo (KMC) simulations of surface catalytic
processes. This algorithm allows for the direct simulation of reaction
networks containing kinetic processes occurring on vastly disparate
time scales which computationally overburden standard KMC methods.
Previously developed methods for temporal acceleration in KMC were
designed for specific systems and often require a priori information
from the user such as identifying the fast and slow processes. In
the approach presented herein, quasi-equilibrated processes are identified
automatically based on previous executions of the forward and reverse
reactions. Temporal acceleration is achieved by automatically scaling
the intrinsic rate constants of the quasi-equilibrated processes,
bringing their rates closer to the time scales of the slow kinetically
relevant nonequilibrated processes. All reactions are still simulated
directly, although with modified rate constants. Abrupt changes in
the underlying dynamics of the reaction network are identified during
the simulation, and the reaction rate constants are rescaled accordingly.
The algorithm was utilized here to model the Fischer–Tropsch
synthesis reaction over ruthenium nanoparticles. This reaction network
has multiple time-scale-disparate processes which would be intractable
to simulate without the aid of temporal acceleration. The accelerated
simulations are found to give reaction rates and selectivities indistinguishable
from those calculated by an equivalent mean-field kinetic model. The
computational savings of the algorithm can span many orders of magnitude
in realistic systems, and the computational cost is not limited by
the magnitude of the time scale disparity in the system processes.
Furthermore, the algorithm has been designed in a generic fashion
and can easily be applied to other surface catalytic processes of
interest.