For many years, scientists did not fully understand how and why metals and alloys sometimes cracked. The mystery was finally solved in the early 1980s, when Murray Daw and Mike Baskes at Sandia National Laboratories developed a way to accurately describe the embrittlement of steel by hydrogen or other corrosive impurities, a problem of interest in defense applications. Using concepts from density functional theory, they constructed the embedded atom method (EAM) from a "first principles" quantum mechanical framework for describing metal bonding. The EAM simplified the quantum behavior so that high-speed calculations could easily be made on very large systems containing hundreds of thousands of atoms. Whereas most fracture studies previously had been conducted on scales of inches or even feet, the EAM revealed much finer detail by focusing instead on atomic-scale processes, such as slight movements of electrons that weaken metal bonds. The EAM accurately describes important quantities such as cohesion and deformation of metals, making possible computer simulations that are useful in designing and predicting the behavior of complex materials and engineering components.

Scientific Impact: The EAM revolutionized computational materials science by enabling large-scale simulations of the atomic structure and evolution of metals; the method successfully simulates complex processes such as metal deformation, embrittlement, and fracture. The method is currently used by more than 100 groups worldwide and has resulted in more than 1,000 published works with more than 2,700 citations to the original paper.

Social Impact: The EAM is used in industry to design alloys for use in metallic parts and products.

Reference: "Parallel Molecular Dynamics With the Embedded Atom Method", S. J. Plimpton and B. A. Hendrickson, in Materials Theory and Modelling, edited by J. Broughton, P. Bristowe, and J. Newsam, MRS Proceedings 291, Pittsburgh, PA, 1993, p 37.

URL: http://www.cs.sandia.gov/~sjplimp/docs/paradyn/README

Technical Contact: Don Freeburn, Office of Basic Energy Sciences, 301-903-3156

Press Contact: Jeff Sherwood, DOE Office of Public Affairs, 202-586-5806

SC-Funding Office: Office of Basic Energy Sciences