Full-Potential KKR Calculations for Interaction Energies in Al-Rich AlX (X = H∼Sn) Alloys: I. Fundamental Features and Thermal Electronic Contribution due to Fermi-Dirac Distribution

Abstract

We presented systematical ab-initio calculations for the n-body (n = 1∼4) interaction energies (IEs) in Al-rich AlX (X = H∼Sn) alloys, by using the full-potential Korringa-Kohn-Rostoker Green’s function (FPKKR) method, and clarified the fundamental features and the thermal electronic contribution due to the Fermi Dirac (FD) distribution for these IEs. We show the calculated results for the IEs: (1) the 2-body IEs of the X = 3d and 4d impurities are strongly repulsive at the 1st-nearest neighbor (nn) and show the oscillating behavior with the interatomic distance; (2) the 1st-nn 2-body IEs of the X = Ne, Ar, and Kr (inert gas elements) impurities are strongly attractive; (3) the 1st-nn 2-body IEs around X = N (2sp element) are repulsive and relatively high; (4) the thermal electronic contribution due to the FD distribution is considerably high for the X = d impurities, while very low for the X = sp impurities; (5) the n-body (n = 1∼4) IEs of the X = 3d and 4d impurities in Al and the thermal electronic contribution for these n-body IEs may be in general lower and lower with the increase in n. It is also discussed that the fundamental features (attraction or repulsion) of the calculated 2-body IEs may be understood by considering the strength differences among the X–X, Al–X, and Al–Al interactions.

Fig. 7 Distance dependence up to the 20th-nn, for X–X (X = N, Ne, Mg, Mn, Cu, Zn, and Tc) IEs in Al. There are two equivalent sites for the 9th-, 13th-, 16th-, 17th-, and 18th-nn pairs. The k-point set in the irreducible BZ, being equivalent to the 100 × 100 × 100 k-point set in the standard BZ of the Al-host, is used for the k-space integration. The T_FD and lattice parameter are fixed at 800 K and 7.7 a.u., respectively. The IEs of Mn–Mn (3d-3d) and Tc–Tc (4d-4d) interaction are oscillating and long-ranged by the strong sp-d interaction of Al–Mn and Al–Tc, respectively. See the text for details.