Inverse Monte Carlo calculation of the effective pair interactions in FePd

Warren-Cowley short-range order parameters deduced from diffuse neutron scattering in an FePd single crystal have been used to calculate the effective pair interaction energies using an inverse Monte Carlo method. The pair interaction energies agree well with those obtained recently using an inverse cluster variation method and show a strong attraction between second-nearestneighbour like atoms. The inverse Monte Carlo calculations show, in contrast to the direct cluster variation method, that the pair interactions in FePd are vanishing beyond the sixth atomic shell. The relevance of the calculated pair interactions is tested in terms of the order-disorder transition temperature simulation. A satisfactory agreement with the experimental value is observed.