N+-N long-range interaction energies and resonance charge exchange

The aerothermodynamic studies of proposed space missions require atmospheric charge-transfer data. ${\mathrm{N}}_2$ ${\mathrm{}}^{+}$ eigenstate energies are calculated with use of the complete-active-space self-consistent-field method with an extended Gaussian basis set. The ${\mathrm{N}}^{+}$-N charge-exchange cross section, determined from these energies, agrees with merged-beam measurements. This contradicts the previous theoretical conclusion. A simple physical description of the long-range interaction is presented and should expedite future charge transfer studies.