Embedded atom method potentials for Al-Pd-Mn phases

A novel embedded atom method (EAM) potential for the $\Xi$ phases of Al-Pd-Mn has been determined with the force-matching method. Different combinations of analytic functions were tested for the pair and transfer part. The best results are obtained if one allows for oscillations on two different length scales. These potentials stabilize structure models of the $\Xi$ phases and describe their energy with high accuracy. Simulations at temperatures up to 1200 K show very good agreement with ab initio results with respect to stability and dynamics of the system.

Figure 1

Scatter plot for energies and forces with the EAM values on the vertical axis and the ab initio reference data on the horizontal axis. The insets are magnified by a factor 4.5.

Figure 2

Detailed structure of the pseudo-Mackay icosahedral cluster. A few atoms of the second and third shell are omitted to see the central atom and the aluminum atoms in the first shell. The icosahedron and icosidodecahedron are indicated by planes and bars, respectively. The central atom is manganese. Aluminum atoms are depicted in yellow (light gray) and palladium atoms in magenta (dark gray).

Figure 3

Comparison of the ab initio formation enthalpy $\Delta H$ (in eV/atom) with the three potential models. The lines between the ab initio data points are added as a guide to the eye.

Figure 4

Difference of the cohesive energy to the convex hull for different amounts of aluminum atoms in the inner shell of the PMI clusters. The data points for model I are shifted by $+$10 meV/atom and by $+$5 meV/atom for model II.

Figure 5

Plots of the 12 functions of the EAM potential (model III) for Al-Pd-Mn.