Analytical methods for calculation of interatomic potentials through the data on the short-range order in alloys

Within the framework of the high-accuracy ring approximation elaborated by the authors (Chepulskii R V and Bugaev V N 1998a, b J. Phys.: Condens. Matter 10 7309-26, 7327-48) in the context of the modified thermodynamic perturbation theory as applied to the lattice gas model, two methods are developed for calculation of the atomic interaction parameters in binary disordered alloys with Bravais crystal lattices through the data on the atomic short-range order (SRO)--the iteration method resulting in explicit analytical relationships and the variational method. Within both methods, the Fourier components of SRO parameters are used as initial data, thus, the most complete information on SRO in the alloy is taken into account. Both the iteration and variational methods permit us to calculate the atomic interaction parameters for an arbitrary number of the coordination shells as well as the Fourier components of the atomic interaction potentials. It is demonstrated that both methods have wide temperature-concentration intervals of applicability. The methods can be used under investigation not only of alloys, but also of other lattice systems (including low-dimensional ones, semiconductors and magnetics). Material discussed: Ni sub 0.89 Cr sub 0.11 .