Hyperthermal collisions of O⁺(⁴S_3/2) with methane at 5 electron volts

Preliminary studies were carried out for the O⁺(4S _3/2) + methane reaction, which serves as a benchmark for developing the theory of polymer erosion by O⁺ under low Earth orbit conditions. Ab initio electronic structure calculations show that the interaction of O ⁺ with CH₄ can lead to a large number of reaction products such as charge transfer, hydride abstraction, and H elimination. Based on the information obtained from these quantum chemistry calculations, a direct dynamics classical trajectory simulation was carried out at 5-eV relative translation energy and the chemical reaction channels predicted by the ab initio calculations are confirmed.