ORDER AND DISORDER IN NI3V - EFFECTIVE PAIR INTERACTIONS AND THE ROLE OF ELECTRONIC EXCITATIONS

In situ neutron diffuse scattering experiments were performed on disordered Ni3V. Effective pair interactions (EPI) were deduced from the measured short-range order parameters. The EPI were used to predict successfully the disordering temperature and the temperature dependence of the excess free energies of two different antiphases in the ordered phase. We also computed the energy difference between DO22 and L12: our result is eight times lower than found by electronic structure calculations at 0 K. This discrepancy is partly due to electronic excitations. © 1994 The American Physical Society.