Atomistic simulations for material processes within multiscale method

  • Atomistische Simulationen für die Material-Prozesse innerhalb Multiscale-Methode / vorgelegt von Chol-Jun Yu

Yu, Chol-Jun; Emmerich, Heike (Thesis advisor)

Aachen : Publikationsserver der RWTH Aachen University (2009)
Dissertation / PhD Thesis

Aachen, Techn. Hochsch., Diss., 2009

Abstract

Atomistic simulation technique such as first-principles, molecular dynamics and Monte Carlo methods has been recognised as a powerful engineering tool to design a new functional material. It serves as the most fundamental procedure to construct a reliable and integral multiscale simulation framework, as well as gives the mechanisms behind the characteristic property and process at atomic scale. In this work some attempts to realize a kind of multiscale simulation have been carried out, paying attention to the necessary information availabe from smaller scale simulations for larger scale simulations. Firstly, an efficient first-principles approach with virtual crystal approximation is proposed for calculating the material properties of solid solutions within density functional theory. The capability of the previous approaches was extended to treat a virtual atom composed of the heterovalent atoms with reasonable accuracy. Secondly, a way to connect the first-principles simulation to the Monte Carlo simulation is presented, applying to surface phenomena. In this attempt the fundamental energetics was calculated with detailed atomic morphology of the surface structure by means of the first-principles simulations, which are utilised in larger scale Monte Carlo simulation to simulate larger scopic morphology and fast kinetic process. Thirdly, molecular dynamics simulations have been performed to calculate the material parameters for continuum scale phase field simulations. The first-principles simulation results are utilised to construct the interatomic potential in the embedded atom method, and the results of molecular dynamics simulations are served as the phase field parameters.

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