# O($^3P$)+CO$_2$ scattering cross sections at superthermal collision energies for planetary aeronomy

## TL;DR

This study provides new quantum-mechanical calculations of elastic and inelastic scattering cross sections for O($^3P$)+CO$_2$ collisions at superthermal energies, crucial for understanding atmospheric escape processes on planets like Mars and Venus.

## Contribution

The paper introduces first-principles computed cross sections using ab-initio potential energy surfaces and quantum scattering methods, improving accuracy over previous models.

## Key findings

- Elastic cross sections are 35% lower at 0.5 eV and over 50% lower at 4+ eV than previously used values.
- Momentum transfer cross sections are lower than those predicted by mass-scaling.
- New data are important for modeling atmospheric escape in planetary atmospheres.

## Abstract

We report new elastic and inelastic cross sections for O($^3P$)+CO$_2$ scattering at collision energies from 0.03 to 5 eV, of major importance to O escape from Mars, Venus, and CO$_2$-rich atmospheres. The cross sections were calculated from first principles using three newly constructed ab-initio potential energy surfaces correlating to the lowest energy asymptote of the complex. The surfaces were restricted to a planar geometry with the CO$_2$ molecule assumed to be in linear configuration fixed at equilibrium. Quantum-mechanical coupled-channel formalism with a large basis set was used to compute state-to-state integral and differential cross sections for elastic and inelastic O($^3P$)+CO$_2$ scattering between all pairs of rotational states of CO$_2$ molecule. The elastic cross sections are 35\% lower at 0.5 eV and more than 50\% lower at 4+ eV than values commonly used in studies of processes in upper and middle planetary atmospheres of Mars, Earth, Venus, and CO$_2$-rich planets. Momentum transfer cross sections, of interest for energy transport, were found to be lower than predicted by mass-scaling.