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Supporting Information
Investigation of ion induced bending mechanism
for nanostructures
Nitul S Rajput*, Zhen Tong* and Xichun Luo*§
*Department of Design, Manufacture and Engineering management,
University of
Strathclyde, Glasgow G1 1XQ, United Kingdom
Caption for movie Movie S1 The Scanning Ion Microscopy (SIM)
video shows the bending of a Si
nanowire upon irradiating by a 16 keV, 21 pA Ga ion beam. The
nanowire bends towards
the side of the ion beam direction.
Molecular Dynamics simulation: For the simulation, we have used
Large-scale Atomic/Molecular Massively Parallel
Simulator (LAMMPS), a classical molecular dynamics code managed
and distributed by
Sandia National Laboratories, US.1 As described in the main
manuscript, the cylindrical
§ Corresponding address: Prof. Xichun Luo.
Email:[email protected]
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nanopillar was built with a diameter of 21.7 nm and height of
43.4 nm. The pillar was
composed of 806, 466 atoms in total.
For the visualization of the atoms, Visual Molecular Dynamics
(VMD) was used.2
The Tersoff.ZBL Potential function gives the energy E of a
system of atoms as:
12 iji j i
E V≠
= ∑∑ (1)
(1 ( )) ( )ZBL Tersoffij ijij ij ijF Ff fV V Vr r= − + (2)
( )
1( )1 F ij CijF A r r
f re− −
=+
(3)
where the 𝑉!"!"# and 𝑉!"!"#$%&& indicate ZBL portion and
Tersoff portion, respectively.
The distance between atoms i and j is rij. The fF term is a
Fermi-like function used to
smoothly connect the ZBL repulsive potential with the Tersoff
potential. There are two
parameters used to adjust it: AF and rC. AF controls how "sharp"
the transition is between
the two portions, and rC is essentially the cutoff distance for
the ZBL potential. The
parameters of Tersoff.ZBL Potential function used in present MD
simulation are shown
in Table S1.
Parameters Ga Si m 1 1 γ 1 1 λ! 0 0 c 7.6298×10!! 1.0039×10! d
1.9796×10! 1.6217×10!
cos θ! 7.1459×10!! −5.9825×10!! N 3.47290 7.8734×10!! β
2.3586×10!! 1.1000×10!!
λ! Å!! 1.7154 1.7322 B eV 1.14786×10! 4.7118×10! R Å 2.8 2.7
D 0.1 0.15 λ! Å!! 3.2834 2.4799
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A eV 2.83982×10! 1.8308×10! Zi 31 14 Zj 31 14
Table S1: The parameters used in the potential function
Tersoff.ZBL in the present MD
simulation.
Supplementary Figures:
Figure S1: High resolution TEM image of a FIB fabricated Si NW
depicts the presence of
several crystalline planes at random orientations in the wire.
The inset shows a
convergent beam electron diffraction (CBED) pattern collected
from the NW.
10 nm
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Figure S2: Bright field TEM image of a NW showing deposition of
thick amorphous
layers on some portions of the wire; (a) before and (b) after
excessive e-beam irradiation.
References:
(1) http://lammps.sandia.gov/index.html.
(2) Humphrey W.; Dalke A.; Schulten, K. J. Molec. Graphics 1996,
14.1, 33.
100 nm 100 nm
(b) (a)
Amorphous layers
