An iterative procedure is introduced to make the results of some simple combining rules compatible with the Tang-Toennies potential model. The method is used to calculate the well locations R-e and the well depths D-e of the van der Waals potentials of the mixed rare gas systems from the corresponding values of the homo-nuclear dimers. When the "sizes" of the two interacting atoms are very different, several rounds of iteration are required for the results to converge. The converged results can be substantially different from the starting values obtained from the combining rules. However, if the sizes of the interacting atoms are close, only one or even no iteration is necessary for the results to converge. In either case, the converged results are the accurate descriptions of the interaction potentials of the hetero-nuclear dimers. (C) 2017 Elsevier B.V. All rights reserved.