First-principles calculation of mechanical properties of Si⟨001⟩ nanowires and comparison to nanomechanical theory

Byeongchan Lee and Robert E. Rudd
Phys. Rev. B 75, 195328 – Published 21 May 2007

Abstract

We report the results of first-principles density functional theory calculations of the Young’s modulus and other mechanical properties of hydrogen-passivated Si⟨001⟩ nanowires. The nanowires are taken to have predominantly {100} surfaces, with small {110} facets according to the Wulff shape. The Young’s modulus, the equilibrium length, and the constrained residual stress of a series of prismatic beams of differing sizes are found to have size dependences that scale like the surface area to volume ratio for all but the smallest beam. The results are compared with a continuum model and the results of classical atomistic calculations based on an empirical potential. We attribute the size dependence to specific physical structures and interactions. In particular, the hydrogen interactions on the surface and the charge density variations within the beam are quantified and used both to parametrize the continuum model and to account for the discrepancies between the two models and the first-principles results.

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  • Received 26 January 2007

DOI:https://doi.org/10.1103/PhysRevB.75.195328

©2007 American Physical Society

Authors & Affiliations

Byeongchan Lee and Robert E. Rudd*

  • Lawrence Livermore National Laboratory, University of California, L-415, Livermore, California 94551, USA

  • *Electronic address: robert.rudd@llnl.gov

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Issue

Vol. 75, Iss. 19 — 15 May 2007

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