Vicinage effects in the stopping power of molecular hydrogen in aluminum

Using time-dependent density functional theory (TDDFT) we calculate the electronic stopping power of the hydrogen molecule, H₂, projectile in aluminum over a wide range of velocities where we take into account the effect of the drag dynamics of excited electrons. The electronic excitations determine the stopping power and also a change the interatomic forces of the molecule during the trajectories.

We observed that the stopping power strongly depends on the orientation of the H₂ molecule and differs significantly from the stopping of He and (twice) the stopping of H. The position of the maximum stopping changes from v = 1.3 a.u. for H to v = 1.8 a.u. for H₂ projectiles. We also study the effect of the interatomic forces and equilibrium distances as a function of the projectile velocity, allowing us to make a prediction of the behavior of the molecule during the stopping process. Our results agree with the available experimental results for the stopping of H₂ molecules in aluminum thin films and allows us to understand those results.