Tutorial #2 // Multiscale modelling of ion-solid interactions
Sunday, July 1, 2018
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TUT-Nordlund
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4:00 PM
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5:30 PM
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Tutorial #2 // Multiscale modelling of ion-solid interactions
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at the Ganil
By Kai Nordlund // Helsinki University, Finland
I will give a tutorial of multiscale modelling of materials, focusing of aspects most relevant to ion-solid interactions. I will first overview how different kinds of simulation methods can be used to simulate different time and length scales. I will then present three methods in greater detail: binary collision approximation (BCA), molecular dynamics (MD) and kinetic Monte Carlo (KMC).
For the BCA method, I will first present the general algorithm for treating successive binary collisions, and different varieties of how it is implemented. I will also describe what its low-energy limit is, and a recent implementation of BCA for arbitrary atomic structures, suitable for simulation of Rutherford back-scattering/channeling.
I will also present the molecular dynamics (MD) method in general, and then describe special features that are needed to make the MD method suitable for efficient simulations of irradiation effects. These include recipes how to add realistic high-energy potentials, include electronic stopping, and use an adaptive time step. I will also describe MD simulations in the recoil interaction approximation (RIA), and how such simulations can be used to get a comprehensive view of ion channeling.
Finally, I will describe the KMC approach, that allows simulating the migration of irradiation-induced defects up to macroscopic time scales. I will first present the KMC algorithm, and describe how the basic approach is very powerful as it can be considered an "exact but stochastic" simulation method. However, KMC is completely dependent of its input data set, and this limitation will be described. As a recent example I will describe recent developments of a KMC approach for simulating W fuzz formation.
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