I made this chat room thinking that it would be as simple as spending 5 minutes adding feeds from Chem.SE, 5 minutes for Physics.SE, 2 minutes for ComputationalScience.SE, 2 minutes for Engineering.SE, and maybe some time on considering what to import from AI.SE, QuantumComputing.SE, Math.SE, MathOverflow.SE, Stats.SE, Biology.SE, DataScience.SE, OpenSource.SE, Astro.SE, and Space.SE.
It turned out to be a much more difficult process than I ever imagined.
So far I have added the following feeds from Chem.SE alone:
The following are other tags in Chem.SE that at least I personally am interested in (but they might not interest you):
https://chemistry.stackexchange.com/questions/tagged/physical-chemistry
https://chemistry.stackexchange.com/questions/tagged/thermodynamics
https://chemistry.stackexchange.com/questions/tagged/molecular-structure
https://chemistry.stackexchange.com/questions/tagged/orbitals
https://chemistry.stackexchange.com/questions/tagged/metal
https://chemistry.stackexchange.com/questions/tagged/electronic-configuration
https://chemistry.stackexchange.com/questions/tagged/molecular-orbital-theory
https://chemistry.stackexchange.com/questions/tagged/crystal-structure
https://chemistry.stackexchange.com/questions/tagged/transition-metals
https://chemistry.stackexchange.com/questions/tagged/materials
https://chemistry.stackexchange.com/questions/tagged/hybridization
https://chemistry.stackexchange.com/questions/tagged/intermolecular-forces
https://chemistry.stackexchange.com/questions/tagged/solid-state-chemistry
https://chemistry.stackexchange.com/questions/tagged/entropy
https://chemistry.stackexchange.com/questions/tagged/free-energy
https://chemistry.stackexchange.com/questions/tagged/chirality
https://chemistry.stackexchange.com/questions/tagged/valence-bond-theory
https://chemistry.stackexchange.com/questions/tagged/vsepr-theory
https://chemistry.stackexchange.com/questions/tagged/kinetic-theory-of-gases
https://chemistry.stackexchange.com/questions/tagged/electromagnetic-radiation
https://chemistry.stackexchange.com/questions/tagged/chemical-engineering
https://chemistry.stackexchange.com/questions/tagged/semiconductors
https://chemistry.stackexchange.com/questions/tagged/physical-organic-chemistry
https://chemistry.stackexchange.com/questions/tagged/ligand-field-theory
https://chemistry.stackexchange.com/questions/53510/how-are-van-der-waals-parameters-determined-experimentally
https://chemistry.stackexchange.com/questions/88585/whats-the-longest-c-c-bond
https://chemistry.stackexchange.com/questions/tagged/computational-chemistry
It's going to be hard to decide which tags to add such that the room is not filling up with new questions every 30 seconds, while also making it so that none of us miss questions that we might find interesting.
Unfortunately all active questions from all the feeds I already added, are already landing in the chat room mostly simultaneously, so for the first couple weeks the room will look a bit overwhelming and we won't really have a clear idea of what it will look like in practice (when all the initial front loading is over and we see the questions being added in "real-time" as they get asked).
I know a lot of people will have objections to many of the tags I suggested above, because I added pretty much everything that I personally like. Instead of hearing all the different things that each person objects to, at the risk of others that object to the objection jumping in and playing ping-pong back-and-forth to debate whether or not to keep a tag, how about we hear from people if there are any specific tags that people absolutely do want to be in the feeds?
I don't expect anyone to answer or have any clear opinion on this until a couple weeks from now when we see what the chat room looks like once things there are settled a bit, but I'm writing this here now so that people can starting thinking about it!
On a related note: I wonder if anyone knows any way to get a graphical visualization of the connectivity matrix representing tags and how they're related to each other? I noticed that questions with tags like basis-set and multi-reference almost(?) 100% of the time also had the tag computational-chemistry or quantum-chemistry, so it wasn't necessary to add those tags (though I still did, since we would surely want anything that is missed by those tags too). However this would help in making the decisions for some of the suggested tags I didn't add yet, because maybe all the questions we're interested in from that tag are already covered by another tag.