H3 Potential Energy Surface
If you can calculate one point to better than 0.01 kcal/mol, you can calculate 100 points to 0.1 kcal/mol just as easily. Spreading these points out gives you a potential energy surface, which is used in classical (shown here) and quantum scattering calculations.
Just enough energy
In this figure and animation, just enough translational energy is supplied to cross the potential energy barrier.
Additional vibrational energy
Additional energy was added to the vibration of the target H2 molecule, causing the reaction not to proceed. The shape of the entire potential energy surface can affect reaction dynamics, not just the height of the barrier.
Extra translational energy
Extra translational energy makes the reaction more certain and faster.