Recent molecular dynamics simulations of the growth of ͓Ni 0.8 Fe 0.2 /Au͔ multilayers have revealed the formation of misfit-strain-reducing dislocation structures very similar to those observed experimentally. Here we report similar simulations showing the formation of edge dislocations near the interfaces of vapor-deposited ͑111͒ ͓NiFe/CoFe/Cu͔ multilayers. Unlike misfit dislocations that accommodate lattice mismatch, the dislocation structures observed here increase the mismatch strain energy. Stop-action observations of the dynamically evolving atomic structures indicate that during deposition on the ͑111͒ surface of a fcc lattice, adatoms may occupy either fcc sites or hcp sites. This results in the random formation of fcc and hcp domains, with dislocations at the domain boundaries. These dislocations enable atoms to undergo a shift from fcc to hcp sites, or vice versa. These shifts lead to missing atoms, and therefore a later deposited layer can have missing planes compared to a previously deposited layer. This dislocation formation mechanism can create tensile stress in fcc films. The probability that such dislocations are formed was found to quickly diminish under energetic deposition conditions.

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The requirements for fitting bcc metals within the EAM format are discussed and, for comparative purposes, the EAM format is cast in a normalized form. A general embedding function is defined and an analytic first- and second-neighbor model is presented. The parameters in the model are determined from the cohesive energy, the equilibrium lattice constant, the three elastic constants, and the unrelaxed vacancy formation energy. Increasing the elastic constants, increasing the elastic anisotropy ratio, and decreasing the unrelaxed vacancy formation energy favor stability of a close-packed lattice over bcc. A stable bcc lattice relative to close packing is found for nine bcc metals, but this scheme cannot generate a model for Cr because the elastic constants of Cr require a negative curvature of the embedding function.

The modified embedded atom method (MEAM) is an empirical extension of embedded atom method (EAM) that includes angular forces. The MEAM, which has previously been applied to the atoms in the FCC, BCC, and diamond cubic crystal systems, has been extended to the HCP crystal structure. Parameters have been determined for HCP metals that have c/a ratios less than ideal. The model is fitted to the lattice constants, elastic constants, cohesive energy, vacancy formation energy, and the BCC-HCP structural energy difference of these metals and is able to reproduce this extensive data base quite well. Structural energies and lattice constants of the HCP metals in a number of cubic structures are predicted. The divacancy is found to be unbound in all of the metals considered except for Be. Stacking fault and surface energies are found to be in reasonable agreement with experiment.

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A procedure based on the embedded atom method (EAM) is presented for developing atomistic models for use in computer simulation calculations, with an emphasis on simple but general schemes for matching experimental data with fitting parameters. Both the electron density function and the two-body potential are taken as exponentially decreasing functions and the model is derived for any choice of cutoff distance. The model has been applied successfully to seven fee and three hep metals, but the extension to bec metals was unsuccessful because of difficulty in matching the shear anisotropy ratio.