MOMENTUM-TRANSFER COLLISION FREQUENCY OF O+-O

The interaction of the thermosphere and ionosphere is largely governed by collisions between ions and neutral particles. On Venus and the Ea rth, O+ is a dominant ion, and atomic O dominates throughout much of t he thermosphere; therefore an accurate O+-O cross section is an import ant prerequisite for understanding the dynamics of planetary upper atm ospheres. The cross section and momentum transfer collision frequency are calculated with a quantum mechanical code which includes resonance charge exchange, polarization, and charge-quadrupole effects. Our res ults agree well with earlier calculations of Stubbe [1968] and Stallco et al. [1991].