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A dynamical mean field theory for the study of surface diffusion constants |
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| Authors: | T Hjelt I Vattulainen J Merikoski T Ala-Nissila S C Ying |
| Institution: | a Helsinki Institute of Physics, PO Box 9 (Siltavuorenpenger 20 C), FIN-00014 University of Helsinki, Helsink, Finland b Department of Physics, Box 1843, Brown University, Providence, RI 02912, USA c Department of Physics, University of Jyväskylä, PO Box 35, FIN-40351, Jyväskylä, Finland d Laboratory of Physics, Tampere University of Technology, PO Box 692, FIN-33101, Tampere, Finland |
| Abstract: | We present a combined analytical and numerical approach based on the Mori projection operator formalism and Monte Carlo simulations to study surface diffusion within the lattice-gas model. In the present theory, the average jump rate and the susceptibility factor appearing are evaluated through Monte Carlo simulations, while the memory functions are approximated by the known results for a Langmuir gas model. This leads to a dynamical mean field theory (DMF) for collective diffusion, while approximate correlation effects beyond DMF are included for tracer diffusion. We apply our formalism to three very different strongly interacting systems and compare the results of the new approach with those of usual Monte Carlo simulations. We find that the combined approach works very well for collective diffusion, whereas for tracer diffusion the influence of interactions on the memory effects is more prominent. |
| Keywords: | Computer simulations Surface diffusion |
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