Roadrunner supercomputer simulates nanoscale material failure

Oct 29, 2009

Very tiny wires, called nanowires, made from such metals as silver and gold, may play a crucial role as electrical or mechanical switches in the development of future-generation ultrasmall nanodevices.

Making nanodevices work will require a deep understanding of how these and other nanostructures can be engineered and fabricated as well as their resultant strengths and weaknesses. How mechanical properties change at the nanoscale is of fundamental interest and may have implications for a variety of nanostructures and nanodevices.

A major limiting factor to this understanding has been that experiments to test how deform are many times slower than computer simulations can go, resulting in more uncertainty in the predictions than scientists would like.

"Molecular dynamics simulations have been around for a long time," said Arthur Voter of the Theoretical Division at Los Alamos National Laboratory. "But the simulations have never before been able to mimic the atomistic tensile strength of nanowires at time scales that even come close to experimental reality."

Using the "parallel-replica dynamics" method for reaching long time scales that Voter developed, members of Voter's team adapted their computer code to exploit the Roadrunner supercomputer's hybrid architecture, allowing them to perform the first-ever simulation of a stretching silver nanowire over a period of a millisecond, or one-thousandth of a second, a time that approaches what can be tested experimentally.

"Bigger supercomputers have made it possible to perform simulations on larger and larger systems, but they have not helped much with reaching longer times -- the best we can do is still about a millionth of a second. However, with the parallel-replica algorithm, we can utilize the large number of processors to 'parallelize' time," said Voter. "Roadrunner is ideally suited to this algorithm, so now we can do simulations thousands of times longer than this."

With this new tool, scientists can better study what nanowires do under stress. "At longer time scales we see interesting effects. When the wires are stretched more slowly, their behavior changes -- the deformation and failure mechanisms are very different than what we've seen at shorter time scales," said Voter.

Through these simulations, Voter and his team are developing a better understanding of how materials behave when they are reduced to the size scale of a nanometer, or one-billionth of a meter. "At this scale, the motion of just one single atom can change the material's mechanical or electrical properties," said Voter, "so it is really helpful to have a tool that can give us full atomic resolution on realistic time scales, almost as if we are watching every atom as the experiment proceeds."

Source: Los Alamos National Laboratory (news : web)

Explore further: Engineers show light can play seesaw at the nanoscale

add to favorites email to friend print save as pdf

Related Stories

Scientists See Smallest-Ever Square Nanotube

Feb 20, 2009

(PhysOrg.com) -- Scientists have observed the smallest reported nanotube that has a square cross-section. The structure formed spontaneously and unexpectedly when silver nanowires were stretched and is a reminder ...

Seeing the unseen universe

Aug 01, 2006

A new method for incorporating astronomical observational data into computer simulations promises to be a significant advance in enabling future cosmological surveys aimed at understanding dark energy and dark matter. Dark ...

Scientists find why conductance of nanowires vary

Feb 05, 2007

A Georgia Tech physics group has discovered how and why the electrical conductance of metal nanowires changes as their length varies. In a collaborative investigation performed by an experimental team and ...

Recommended for you

Engineers show light can play seesaw at the nanoscale

6 hours ago

University of Minnesota electrical engineering researchers have developed a unique nanoscale device that for the first time demonstrates mechanical transportation of light. The discovery could have major ...

A nanosized hydrogen generator

Sep 20, 2014

(Phys.org) —Researchers at the US Department of Energy's (DOE) Argonne National Laboratory have created a small scale "hydrogen generator" that uses light and a two-dimensional graphene platform to boost ...

For electronics beyond silicon, a new contender emerges

Sep 16, 2014

Silicon has few serious competitors as the material of choice in the electronics industry. Yet transistors, the switchable valves that control the flow of electrons in a circuit, cannot simply keep shrinking ...

Making quantum dots glow brighter

Sep 16, 2014

Researchers from the University of Alabama in Huntsville and the University of Oklahoma have found a new way to control the properties of quantum dots, those tiny chunks of semiconductor material that glow ...

User comments : 0