Low-energy proton impact dynamics on hydrocarbons: Dependence on kinetic energy and incident site

The dynamics of low-energy proton collisions with hydrocarbon molecules are investigated using real-time time-dependent density functional theory. Through systematic variation of proton kinetic energy and impact site on the molecular surface, the resulting scattering, proton capture, and bond dissociation pathways are analyzed. The simulations reveal a strong dependence of reaction outcomes on both incident energy and collision geometry, with the interplay between electronic and nuclear degrees of freedom highlighted as governing molecular fragmentation and reaction mechanisms. These findings provide insight into the fundamental processes underlying proton–hydrocarbon interactions relevant to radiation chemistry, ion-beam processing, astrochemical environments, and Coulomb explosion.