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The Size Effect of Coarse-Grained Modeling for Nonlinear Behavior of Nano-Structure Materials

Khademabbasi, Navid | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 53173 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Khoei, Amir Reza; Jahanshahi, Mohsen
  7. Abstract:
  8. The development of Nanotechnology increasingly has elevated the urgency for the expansion of modern numerical and computational methods that have evaluating systems with capability at this scale. In spite of being fully capable of evaluating nanostructures, the existing techniques, such as Molecular Dynamics Methods, lack the ability to simulate large systems of practical size and time scales. Thus, being able to create a large model of realistic simulation, which is confined by the computational expense of the running Molecular Dynamics methods at hand, Coarse-Graining technique has recently become a very effective and beneficial method which refers to the development of simplified models of molecular systems with reduced number of degrees of freedom which is achieved by reducing the number of interaction sites, resulting in a model that is computationally less expensive than the original atomistic model. Until now, the Coarse-Grained models have been used to simulate huge biomolecules lonely such as proteins, lipids, DNA, and polymers since they have including massive and complex structures which make them impossible to be modeled by former molecular methods available. However, in this research, we have focused on applying the Iterative Boltzmann Inversion Coarse-Graining Technique to FCC metal crystal structures in order to be able to simulate larger models of practical size, modeling of which would be time and energy consuming by the molecular dynamic methods available. In this particular technique, the goal is to determine a Coarse-Grained potential for size of twice, triple and quadruped in such a way that the target radial distribution function of the reference all-atom system, which structurally specify the atomistic system, is reproduced. At the beginning of this research, no actual coarse-graining performed, and the aim was to develop an interatomic potential for the all-atom system using the Iterative Boltzmann Inversion method to verify the approach. Once the effectiveness of the IBI method in producing a pair-wise potential to simulate an all-atom model was adequately studied, coarse-graining of variable sizes conducted, and the mechanical behavior of the all-atom system compared to that obtained from coarse-grained systems, the potential of which sizes developed using the IBI method. In the end, the results of the efficiency of different grain-sizes for all of the samples have illustrated
  9. Keywords:
  10. Coarse Grained Model ; Iterative Boltzmann Inversion ; Nanostructure ; Nanotechnology ; Molecular Dynamics ; Crystalline Metals ; Iterative Boltzmann Inversion ; Grain Size

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