MODIFIED EMBEDDED-ATOM POTENTIALS FOR HCP METALS

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.