The migration path of an interstitial atom begins at an equilibrium position, from where the atom moves to the configuration known as the transition state (saddle point) where the lattice experiences maximum strain, as this is the energetically least favorable position along the migration path and then moves to a neighboring interstitial position. In the saddle-point configuration, the surrounding matrix atoms need to move aside to allow the passage for the migrating atom. Conceptually, this represents the most straightforward diffusion mechanism.