Study on Proton Collision Dynamics Inside C₂₀ Fullerene Based on Time-Dependent Density Functional Theory

Using the method of non-adiabatic coupling between time-dependent density functional theory (TDDFT) and molecular dynamics (MD), taking proton-preencapsulated C₂₀ fullerene as the research object, this study explores the collision dynamics between protons with an initial kinetic energy of 5-500 eV and C₂₀. The results show that the ground state of C₂₀ contains two types of pentagonal carbon rings and four types of CC bonds, and the symmetrical distribution of bond lengths ensures structural stability. The interactions between proton and C₂₀ can be classified into three categories: “intracage vibration / bonding”, “cage-breaking bonding”, and “direct separation and escape”, with 40 eV being the critical kinetic energy for cage structure destruction and complete proton escape. The kinetic energy lost by proton has a linear relationship with the incident energy. At low incident energy (≤40 eV), the energy loss rate exceeds 75%, while at high kinetic energy (≥45 eV), the loss rate decreases from 75% to 21%. The strong coupling between electrons and ions drives energy transfer, and the higher the proton energy, the stronger its ability to adsorb electrons from C₂₀, with the number of electrons lost by C₂₀ increasing from 0.8 to 1.9. The research results fill the theoretical gap in proton dynamics inside small-sized fullerenes and provide microscopic theoretical support for the design of fullerene-based proton storage and quantum sensing materials.