A COMBINING RULE CALCULATION OF THE VANDERWAALS POTENTIALS OF THE RARE-GAS HYDRIDES

The van der Waals potentials of the rare-gas hydrides are obtained from potential parameters of the homogeneous rare gas and the H atom interactions in 3-SIGMA H-2 with the aid of combining rules. With one simple modification, the combining rules of Nyeland and Toennies are used to estimate the Born-Mayer [A exp(-bR)] short-range repulsive potential parameters of the rare-gas hydrides. These parameters, together with the dispersion coefficients obtained from the well established combining rules, are used in the Tang-Toennies model to yield the full potential energy curves of the mixed systems. The predicted well parameters for H-Ne, H-Ar, H-Kr and H-Xe are in excellent agreement with experiment, but the predicted well depth of H-He seems to be in error by about 10%. The present results show that the reduced potential curves for the five rare-gas hydrides are almost identical to each other and that they have a somewhat wider potential bowl than that of either 3-SIGMA H-2 or the rare-gas dimers.