What constitutes an on- or off-topic computational question? Can that clarification be added to the help pages?
What constitutes an on- or off-topic computational question?
We might unwittingly be reopening a can of worms here... I am not sure if there is (100%) clear consensus on what is on- and off-topic here. And I am not sure if there are enough active users who care about such questions to form a consensus.
It is pretty clear that "find the typos in my input file"-type debugging questions, or "how do I install this software" questions, are generally considered off-topic. On the other hand, questions more about the theory behind the calculations are also obviously on-topic. The main problem is that there is a grey area in the middle, with things such as (quoting) "How do I set up a geometry optimisation in Gaussian?". Some don't like it, some do. There are very valid arguments for both sides.
The accepted answer, though, seems to suggest that (at least in 2016) the policy is to allow questions in the gray area. So I guess it is fair to say that even though not everybody agrees with it, there is some kind of consensus, as judged by the votes (and green tick). I would prefer having a second opinion on this though...
Can that clarification be added to the help pages?
In my opinion that the first step is not to modify the help pages, but rather to make a FAQ-style post on Meta, describing what sort of questions are on- or off-topic, and why. (The post linked above isn't particularly helpful for a new visitor - it has a lot of back-and-forth, and is probably too confusing to read.)
Once that's done, then the help page can (and should) be updated with a link to this post. I don't think it's possible to summarise the entire discussion within the help page itself.
The Tour page says don't ask "Computational questions". It also says don't ask "Anything not directly related to chemistry". It does not say don't ask about "Computational chemistry".
For example, if I want to get the total mass of a solution where 5.0 g of sodium chloride dissolved in 200.0 g of water, and I already know I have to add the two masses, but don't know how, that question would be a bad fit. First, because it is a computational question, and second, because it is not directly related to chemistry.
I would think that "Anything not directly related to chemistry" is sufficient for the tour, and "Computational questions" could be dropped. There might be places elsewhere for collecting the most annoying types of question that are bad and keep coming up. I would suspect that these would change over time. For example, it might have been a problem to solve a cubic equation numerically in the past, but now people just use Wolfram Alpha or a similar tool to get the answer.