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Surface excess elasticity of gold: ab initio coefficients and impact on the effective elastic response of nanowires
Citation Link: https://doi.org/10.15480/882.1637
Publikationstyp
Journal Article
Date Issued
2016-11-20
Sprache
English
TORE-DOI
Journal
Volume
124
Start Page
468
End Page
477
Citation
Acta Materialia (124): 468-477 (2017)
Publisher DOI
Scopus ID
Publisher
Elsevier
Predicting the influence of the surface on the effective elastic properties of nanoscale structures and nanomaterials remains a challenge, which we here address on both levels, continuum and atomic. Density Functional Theory (DFT) computation at the atomic level yields the first reliable surface excess elastic parameters for the (111) and (001) surfaces of gold. At the continuum level, we derive closed-form expressions for the effective elastic behavior that can be combined with the DFT-derived excess elastic parameters to obtain the effective axial, torsion, and bending stiffness of circular nanowires with surface excess elasticity. The two approaches use different reference frames, and we emphasize the need for consistent stress definitions and for conversion between the separate stress measures when transferring results between the approaches. We present excess elastic parameters separately for Cauchy and 2nd
Piola-Kirchhoff stresses, demonstrating that the conversion substantially modifies their numerical value and may even invert their sign. The results afford an assessment of the contribution of the surface excess elastic parameters to the effective elastic response of nanoscale beams or wires. This assessment sheds doubt on earlier suggestions relating experimental observations of an effective stiffening or softening at small size to the excess elasticity of clean surfaces.
Piola-Kirchhoff stresses, demonstrating that the conversion substantially modifies their numerical value and may even invert their sign. The results afford an assessment of the contribution of the surface excess elastic parameters to the effective elastic response of nanoscale beams or wires. This assessment sheds doubt on earlier suggestions relating experimental observations of an effective stiffening or softening at small size to the excess elasticity of clean surfaces.
Subjects
surface excess elastic parameters
surface lamé constants
nanoelasticity
nanowire
density functional theory
DDC Class
620: Ingenieurwissenschaften
Publication version
publishedVersion
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