Short-range correlations in binary alloys: Spin model approach to Ag$_c$Pd$_{1-c}$

TL;DR

This paper uses a spin model approach to analyze short-range atomic correlations in Ag-Pd alloys based on ab initio total energy calculations, revealing insights into local ordering tendencies.

Contribution

It introduces a method to extract short-range correlations from total energy data using the Bethe-Peierls-Weiss model for Ag-Pd alloys.

Findings

Positive first neighbor correlator predicted at low temperature.

Correlation analysis relates to optimal alloy structures.

Model successfully inverts total energy to atomic interactions.

Abstract

Short-range correlations in Ag-Pd alloys are investigated by analyzing the {\em ab initio} total energy of fcc based random Ag$_c$Pd$_{1-c}$. Since the information on the atomic interactions is incorporated in the energetics of alloys it is possible with a suitable model, Bethe-Peierls-Weiss model is used in the present work, to invert the problem, i.e.\ to obtain information on the short-range correlation from the total energy of a random system. As an example we demonstrate how site correlations can be extracted from random alloy data. Bethe-Peierls-Weiss model predicts positive first neighbor correlator and mixing energy for substitutional face centered cubic (fcc) Ag-Pd alloys at low temperature which can be related to the optimal structures of Ag$_{0.5}$Pd$_{0.5}$.