Supercomputing van der Waals Forces on Mira

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A wave-like theoretical model for the van der Waals force

A wave-like theoretical model for the van der Waals force

Over at ALCF, Katie Jones writes that researchers are using the Mira supercomputer to validate a new “wave-like” model of the van der Waals force—a weak attraction that has strong ties to function and stability in materials and biological systems. One of the study’s lead authors, Robert A. DiStasio Jr. of Cornell University, is an Argonne Leadership Computing Facility user who develops computational methods for simulating bonded and non-bonded interactions between atoms in realistic systems, notably water, the basic ingredient of many of the materials we use and biological systems we rely upon.

Many new devices for energy technologies, therapeutic drug delivery and high-performance materials are being designed at the nanoscale by manipulating systems at the atomic and molecular levels. Although scientists and engineers have a better understanding and control of materials at the nanoscale than ever before, there are still fundamental questions about how things work exactly at distances where the laws of physics toe the line between our classical understanding and the world of quantum mechanics. That’s why a team of researchers used the Mira supercomputer to simulate the interactions between nanostructures, focusing on a lesser understood force that plays an important role in molecular assembly and function. Unlike ionic or covalent bonds, which are bonds made by attractive electric charges or shared electrons, the van der Waals force is a non-bonded interaction at the nanoscale—which spans distances of about 10 to 1,000 typical chemical bond lengths.

“They’re relatively weak forces. The atoms ‘feel’ each other through space,” said Robert A. DiStasio Jr., assistant professor in the Department of Chemistry and Chemical Biology at Cornell University. “But these non-bonded forces play a crucial role in determining the structure, stability and function in a huge number of systems throughout the fields of biology, chemistry, physics and materials science.”

By simulating nanostructures including one-dimensional nanowires and two-dimensional nanosheets, researchers validated a new “wave-like” theoretical model that predicts better than have previous models how van der Waals forces behave at the nanoscale. One of the world’s five most powerful supercomputers, Mira, an IBM Blue Gene/Q system, is operated by the Argonne Leadership Computing Facility (ALCF), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE’s Argonne National Laboratory.

This study changes how we should think about the manner in which objects interact at the nanoscale,” DiStasio said. “The existence of van der Waals interactions has been known for more than 100 years, but our ability to actually calculate these interactions in realistic systems has exploded over the last 10 years.”

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