Difference Between Tunneling and Hopping: Explained

[citw]

In my research, I've always seen variable range and nearest neighbor hopping referred to as tunneling processes. However, I've also read papers that differentiate tunneling and hopping as two different transport mechanisms. Can someone clear this up for me? Given the context, what exactly is the difference between hopping and tunneling?

 

[Useful nucleus]

In hopping, the hopping particle has to have energy greater than or equal to that of the height of the barrier in order to cross the barrier, in tunnling it can cross the barrier even with energy less than the height of the barrier.

Examples: A heavy ion (let's say anthing heavier than Lithium) usually "hops" from one site to the next in the lattice during diffusion.
On the other hand interstitial proton in proton conductor can "tunnel" through the barrier and also can hop "above" it.

A celebrated example from nuclear physics is the "tunneling" of the alpha particle through the coulombic barrier during alpha decay.

 

[citw]

In hopping, the hopping particle has to have energy greater than or equal to that of the height of the barrier in order to cross the barrier, in tunnling it can cross the barrier even with energy less than the height of the barrier.

This is an interesting interpretation. I don't think I've heard it expressed this way before.