Do we still consider questions about the use of chemical software off-topic?
As a blanket statement, I think questions about the use of chemical software should be on-topic, so no.
If no, should we establish a few guidelines for such questions to prevent them from cluttering our site?
For this to work, we definitely need guidelines.
I wanted to take a small survey of the questions currently under the tag, so here is some sort of arbitrary categorization of the first 50 questions on the "Newest" page. I placed each question into more than one bin where appropriate, but this is completely my biased judgement. P and C are for "program" or "concept", with "?" where it could be disputed or I couldn't decide. Other things I would have done differently: lab software (lots of HPLC stuff) went under "math"/other, and I didn't create the visualization bin soon enough so that's an underestimation.
$$
\small
\begin{array}{clc}
\hline
\textbf{Categorization} & \textbf{Topic} & \textbf{Count} \\
\hline
\text{P} & \text{Amber} & 1 \\
\text{P} & \text{Gaussian} & 10 \\
\text{P} & \text{Open Babel} & 2 \\
\text{P?} & \text{PDB} & 2 \\
\text{P} & \text{Avogadro} & 6 \\
\text{C} & \text{Charges} & 1 \\
\text{C} & \text{Transition states} & 3 \\
\text{C} & \text{"Math"/other} & 9 \\
\text{?} & \text{Technical} & 14 \\
\text{P} & \text{TINKER} & 1 \\
\text{C} & \text{Method comparison} & 1 \\
\text{P} & \text{Other MD package} & 2 \\
\text{C} & \text{Comp. chem. concepts} & 5 \\
\text{P} & \text{What package(s)? (survey)} & 10 \\
\text{P} & \text{GAMESS} & 1 \\
\text{?} & \text{Data source(s)} & 3 \\
\text{C?} & \text{Programming} & 4 \\
\text{P?} & \text{Cheminformatics} & 3 \\
\text{P} & \text{Visualization} & 5 \\
\text{C} & \text{Reference request} & 1 \\
\hline
\end{array}
$$
The "technical" topic is the one we're most interested in here. To draw an analogy, it's the homework of software. Maybe we should create software-homework? I jest, but it's the practicioner's equivalent of homework. It bothers me that so many of the questions revolve around basic usage of a certain program named after a kind of mathematical function, and I wonder if these get a free pass due to it being that program, so any question surrounding it must be complex. There should be more scientific merit to some of these questions. The same goes for Avogadro, most of which are not about visualization techniques but are more user support.
I'd like to bring up Philipp's answer (by no means to pick on it):
I think that question about how use comp chem software should be on topic. For example, the question about how to set up the geometry in Gaussian can be compared on how to set up all the glass ware and whatever else reaction stuff in an actual lab. Those questions then would probably be on topic and receive an answer.
I disagree here, for a few reasons. At least, I think this deserves elaboration.
I was under the impression that "best practices" questions were off-topic. At least, it isn't clear to me from our tour page. "Experimental techniques and technology" are ok, but would it be acceptable for me to ask about tips on running a chromatography column (test solvent system with a pipette column, TLC every x minutes, etc.)? In my opinion, those are things every synthetic chemist should know. They're also opinion-based to a certain degree. Why does this bar seem to be lower for computational chemistry? People probably wouldn't like it if I went around saying "people doing calculations shouldn't use Windows" as a best practice. (Yes, this is pretty extreme.) Do we want to accept questions on best practices?
"Is my input correct?" is dangerous. If it's something like "help me construct my z-matrix", maybe there should be a canonical question with appropriate internet and literature references, but definitely nothing beyond that. Where does something like "What's the difference between calling b3lyp
and td-b3lyp
in Gaussian" fall? One might view it as practicioner's homework, another might view it as a chance to make an important conceptual point.
My PC is my lab and up to a certain point I am doing chemistry there. So, in my eyes those are chemistry problems that will not fit into any other SE better, as they are too specific and we have the expertise for many of those programs around here.
I am in general agreement with this point, but there needs to be some minimum barrier to entry, otherwise the tag will become even more of a mess than it is.
Perhaps something to help us decide what's on-topic is...
Some initial tagging guidelines?
...tags, tags, tags. These questions need more tags.
My thought is that if you cannot envision a question have more than just the software tag, it isn't a good fit for the site. I say this having done so twice out of my four questions asked! One question could have more tags, and the other's quality is debatable.
Summary
Yes, these should be on-topic, but the bar needs to be raised.
I am more focused on questions like "How do I set up a geometry optimisation in Gaussian?" in this post. Strictly speaking they are not chemistry questions and have often been viewed as off-topic here. The question is, whether this should be changed and under what guidelines.
That shouldn't be allowed. I have had good success in luring these people into chat, though.
I realize I'm kind of mixing topics here (best practices vs. "homework questions") and deviating from the question but it's easier for me to air everything at once.
Side notes for later discussion
Other things I discovered in doing research for this answer which aren't pertinent to my answer but don't deserve their own questions quite yet:
Transition state questions seem to be common, both the conceptual and technical aspects. Should there be transition-state for both experiment and computation? This is not the same thing as what's currently under transition-state-theory, which might be subsumed under the new tag.
I think all instances of "Gaussian 09" or "G09" should be changed to "Gaussian". The version being used is inconsequential in all the cases we have, and no one is using other versions.
Someone created nwchem and orca. Do we want to create more program-specific tags, like gaussian or avogadro? In this specific case, these tags have 1 Q and don't make sense to exist since they aren't even NWChem- or ORCA-specific.