|
CNMS
User Research
Molecular
Simulations of Stretching Gold Nanowires in Solvents
Qing
Pu and Yongsheng Leng, (Department of Chemical Engineering, Vanderbilt
University)
Xiongce Zhao and Peter T. Cummings (CNMS, ORNL)
Achievement
Molecular
dynamics and grand canonical Monte Carlo simulations were performed
to study, for the first time, the effect of solvent on the elongation
dynamics and structure of gold nanowires. For a simple Lennard-Jones
solvent (propane), molecular dynamics simulation results demonstrated
that below the melting point of gold nanowires, the solvent effect
on the elongation properties of Au nanowires is minimal. Monte Carlo
simulations were performed to study the self-assemble structure of
benzenedithiol (BDT) molecules on a gold nanowire when it is immersed
a bulk BDT liquid, using the force field for the BDT-Au chemical bonding
developed by several of the authors. The simulation results show that
the packing density of the bonded BDT on the surface of Au nanowire
is greater than that on an extended Au (111) surface.
Significance
Studying the current-voltage (I-V) characteristics of single molecules
is a key step towards the development of practical molecular electronics
devices. Many of the experimental I-V measurements in metal-molecule-metal
junctions have been performed in a solvent where the junctions were created
through mechanical stretching of nanowires. The electronic properties
of these junctions are dependent on both the stretching process and the
environment in which the fabrication is performed. However, the effect
of solvent on the elongation properties of nanowires has not been previously
investigated. Molecular modeling is a natural tool to investigate such
questions. This study is the first theoretical approach to investigate
the solvent effects on the elongation the Au Nanowires. The results from
this paper are helpful in understanding the underlying mechanism of the
formation of Au-BDT-Au junctions implemented in molecular conductance
measurements.
Publications
Qing Pu, Yongsheng Leng, Xiongce Zhao, and Peter T. Cummings, "Molecular
Simulations of Stretching Gold Nanowires in Solvents," Nanotechnology 18,
424007 (2007).
Break-junction configurations of 256-Au (001) nanowire in (a) vacuum
and (b) propane at 300 K.
The equilibrium adsorption configurations of BDT molecules on an Au
(001) nanowire.
(a) Side view (b) top view
|
