INTERACTION POTENTIAL OF K+ IN AR - A MONTE-CARLO SIMULATION MOBILITY-COMPARISON TEST

A standarized Monte Carlo simulation (MCS) procedure is used as a routine test of the accuracy of any interaction potential of an ion-atom binary pair. By capitalizing on the performance of a supercomputer, the procedure achieves a highly realistic simulation of the ionic motion and calculates the resulting mobilities of the ions in the neutral gas. These values are then compared against accurate experimental values, assumed available. For cases where the same interaction potential has also been used as input for kinetic-theory calculations of mobilities, the procedure may be extended to check the accuracy of the theory itself. The interaction potentials of Lamm et al. [J. Chem. Phys. 74, 3042 (1981)]; Budenholzer, Gislason, and Jorgensen [J. Chem. Phys. 78, 5279 (1983)]; and Koutselos, Mason, and Viehland [J. Chem. Phys. 93, 7125 (1990)] for the K+-Ar pair as an illustrative case study are examined. The calculations indicate that the potential of Koutselos, Mason, and Viehland is the most accurate currently available. Furthermore, a comparison of the MCS calculations with the two-temperature theoretical mobilities of Lamm et al. and the three-temperature mobilities of Koutselos, Mason, and Viehland suggests that both theories are quite accurate at both the low- and high-ionic-drift-energy regions, but are up to about 2% too high at the intermediate-energy region.