NSTI Nanotech 2009

Extraction of Bulk Material Properties from Phonon Dispersion Spectra

N. Kumar, K. Pochiraju
Stevens Institute of Technology, US

Keywords: phonon, molecular dynamics

Abstract:

Experimental characterization of mechanical behavior of nanostructures can be cumbersome and expensive. Design of nano-structured materials with properties tailored to meet macro-scale requirements invariably requires model-based understanding of the structure-to -property relationships. In this effort, the elastic and fracture behavior of single crystal materials are studied using equilibrium Molecular Dynamics (MD). The atomic structure of the material simulated with suitable periodic and finite dimension models. The temperature at which the properties are determined is reached by using a slow equilibrium procedure that produces a convergent initial energy and stress states before mechanical loading is applied. Fracture is simulated by creating a crack at the center of the model by removing the interaction between two adjacent planes of atoms. Gold lattices are used in numerical illustrations. The elastic behavior as well as the effect of damage initiation can be observed in the time-domain and frequency-domain responses of stress and energy states in the model. Appropriate comparisons are made between the properties determined from modeling and experimental data from the bulk material.
 
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