Computer simulations are particularly useful in studies of complex systems such as solids with a disordered arrangement of atoms. It is difficult, however, to guess the mechanism of atomic rearrangements in such systems, for example diffusion events and chemical reactions, and it is impractical to construct an exhaustive list of all the possible transitions because no two sites are the same. It is, therefore, important to use an unbiased algorithm to identify the mechanism of possible transitions and estimate their rate. The adaptive kinetic Monte Carlo (AKMC) method is based on saddle point searches initiated by random initial displacements and can be applied to simulations of disordered solids. The method will be presented as well as applications to several systems, including structural optimization and H-atom diffusion in metal grain boundaries [1], H2O diffusion on proton disordered ice Ih(0001) surface [2], and H-adatom diffusion and reaction on low and high density amorphous ice surfaces [3].<br/><br/>[1] A. Pedersen and H. Jónsson, Acta Materialia 57, 4036 (2009).<br/>[2] A. Pedersen, L.J. Karssemeijer, H. M. Cuppen and H. Jónsson, J. Phys. Chem. C 119, 16528 (2015).<br/>[3] V. Ásgeirsson, K.T. Wikfeldt and H. Jónsson (submitted).

Long timescale simulations of diffusion and reactions in and on the surface of disordered solids

251st National Meeting (2016)

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