detecting tunnels

[computron]

Any way to detect that Li forms tunnels / channels in this structure?

https://www.materialsproject.org/materials/mp-504366/

Note that:

• not all the Li sites form tunnels
• the Li sites that do form a tunnel are not bonded to one another, but they would still typically be described as a Li tunnel. e.g. for Li diffusion, it will occur in 1D in those channels.
• It's something like "the presence of a line of Li sites that is uninterrupted by other atoms and with some sphere of "empty space" along the entire line (?)

This might be complicated, but will be nice if it can actually detect it...