Efficient implementation of the concentration-dependent embedded atom method for molecular-dynamics and Monte-Carlo simulations (original) (raw)
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The embedded-atom method (EAM) is a popular tcchni;!ue for the atomic simulation of meals and alloys. The EAM procedure involves two computational phases; the first to e,,aluate electron densities and the second to evatua~e e~ energies and repulsive forces. Substantial computational ce ~ts are required for each phase, particularly for khe simaJafio¢ of large particle systems. On distributed-memory a:i:hitectu~es each phase also requires communication overhead, parallel efficiency. We introduce a pseudo-EAM tPEAM) technique to improve the performaace for particle sim¢~ of metals. The key PEAM procedure is the approximation of electron densities from the previous fimestep, at~,wi~ computations to be performed in a single phase. We demonstrate the efficiency of the PEAM procedure and show ~ R produces identical behavior to EAM systems. On I~oth serial and parallel architectures, PEAM simulations are near|), twice as fast as EAM simulations for the same atomic system.
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Scalable parallel Monte Carlo algorithm for atomistic simulations of precipitation in alloys
We present an extension of the semi-grand-canonical (SGC) ensemble that we refer to as the varianceconstrained semi-grand-canonical (VC-SGC) ensemble. It allows for transmutation Monte Carlo simulations of multicomponent systems in multiphase regions of the phase diagram and lends itself to scalable simulations on massively parallel platforms. By combining transmutation moves with molecular dynamics steps, structural relaxations and thermal vibrations in realistic alloys can be taken into account. In this way, we construct a robust and efficient simulation technique that is ideally suited for large-scale simulations of precipitation in multicomponent systems in the presence of structural disorder. To illustrate the algorithm introduced in this work, we study the precipitation of Cu in nanocrystalline Fe.