Many-body potentials were introduced in the early 1980s and have become a workhorse for the simulation of materials, especially metallic systems. The physical motivations for the main classes of the various many-body potentials are summarized, and the advantages of this approach are discussed. Some current examples related to grain growth, stress generation in thin films, shock loading, and nanowire deformation are presented to illustrate the continuing value of these approaches. Finally, some of the approaches that have been introduced in subsequent years are briefly described.

Modeling cascade and fission damage evolution of actinide materials of all kinds is essential for understanding their aging characteristics. As an example of how exotic some of the damage evolution behavior can be, plutonium-gallium (Pu-Ga) alloys in the δ-phase (fcc lattices) are explored. Aging emanates from the wide variety of spontaneous decay and fission products that, in the case of the Pu, are such species as helium (He) and uranium, among others, as well as interstitials, and vacancies. To aid in our understanding, the modified embedded atom method (MEAM) formalism is applied to the Pu-Ga-He system. The behavior of defects in the fcc (δ) phase of Pu-based materials is strongly influenced by the metastability of this phase. The influence of this metastability on minimum displacement threshold energy, point defect characteristics and He bubbles is delineated. The roles of short-range ordering and transformations of voids into stacking fault tetrahedra in the aging process are also examined.

The computer simulation of the structure and fracture of interfaces on an atomic scale requires a computationally efficient prescription for the total energy that is reliable both for small deviations from the bulk as well as for the free surfaces produced during fracture. The recently developed Embedded Atom Method is such a method. It will be briefly described and compared to traditional pair interaction approaches. In particular, it will be shown that the many-body effects inherent in the Embedded Atom Method are essential to correctly describe the experimentally observed surface reconstructions of Au surfaces.

The necessary first step in simulating the fracture of an interface, such as a grain boundary, is the determination of the initial or equilibrium atomic configuration of the interface. Equilibrium Monte Carlo simulations using the Embedded Atom Method can determine this structure. This approach will be outlined and various results for grain boundary structure in fcc metals will be presented. The atomic structure of symmetric tilt boundaries is found to be significantly different from that deduced from energy minimization techniques. In addition, the Monte Carlo technique allows for the determination of thermal effects such as the vibrational amplitudes at the interface and the thermal expansion of the interface.