What does the ethics divergence value actually mean?

How should the ethics divergence value be interpreted? I understand that negative values means that the pop is more likely to change their ethics to be in line with the empire's values (presumably with larger negative values meaning faster convergence), but what exactly does a smaller or larger positive value mean? What does a value of 0 do? If I want a pop to change their ethics, particularly without caring about what they change it to, how should I try to affect ethics divergence?

Background: My game had a fanatical xenophobe empire going around conquering their neighbors and exterminating their populace. I didn't like this very much, so I declared war and took over a bunch of their worlds. Being fanatical xenophobes, the populace isn't particularly appreciative of my more "enlightened" rule, with a -40% Alien Overlords happiness modifier. This destroys their productivity and makes them join rebellious factions. Getting rid of their xenophobia is sufficient to make them happy and productive citizens again.

As such, I'm trying to get them to change their ways. I don't particularly care what they change to, just that they're no longer fanatically xenophobic. These planets are far from my homeworld, and the populace is "outraged", so the ethics divergence value is higher than the reeducation edict can handle. Furthermore, I don't particularly want them to adopt my ethics either, given that my empire is also xenophobic (though this lesser xenophobia is much more manageable than the current Fanatic, so it's still acceptable). To make them change, do I want to raise or lower ethics divergence?

Ethics divergence is either positive or negative.

If it is positive, it will push your pops' ethics further from your empire's. If it is negative, it will push their ethics toward your empire's. This has been demonstrated in another answer here and the Stellaris wiki.

So, if your empire is xenophobic, and these pops are fanatically xenophobic, then your empire is less xenophobic. Therefore, if you want them to become less xenophobic, you want to push their ethics toward yours. This would require a negative drift.

If you can't get negative, then at least less positive might work. It's not clear to me if the divergence applies equally to each pop, or if it might just be an average of a bell curve.

If you can get some of the pops down to xenophobic, then at some point they might end up less xenophobic than your empire. At this point, you would need a positive drift to continue to reduce their xenophobic tendencies and push them towards xenophilia.