Scientists use world’s fastest computer to simulate nanoscale material failure

Through these simulations, scientists are developing a better understanding of how materials behave at the size scale of a nanometer, or one-billionth of a meter Los Alamos, New Mexico, October 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 nanowires deform are many times slower than computer simulations can go, resulting in more uncertainty in the simulation 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.