I searched through all 296 "materials" questions on the Chem SE: https://chemistry.stackexchange.com/questions/tagged/materials, and looked for questions that also had any of the "computational" or "theory" or "theoretical" tags. In total there was only one!
I then did the same on the Physics SE and found that there was again, only one question that had both a materials tag and a computational tag.
It therefore appears that Materials Modeling questions do not get asked on either SE. A huge number of "computational chemistry" and a huge number of "computational physics" questions get asked on each SE, but it is surprising that not so many get asked for "chemical physics" of materials (questions about chemical physics of gas-phase systems do get asked a lot though, and we can find them by searching the "ab-initio" or "quantum chemistry" tags).
Furthermore, there's 1007 materials modeling questions on Research Gate just on using the software VASP: https://www.researchgate.net/topic/VASP, and 15000+ questions on the VASP forum itself: https://cms.mpi.univie.ac.at/vasp-forum/forum.php, and according to Facebook, there's an average of 2 posts/week on the VASP facebook group: https://www.facebook.com/groups/Vasp.Code/
Then a similar story can be told for other materials modeling software like QuantumEspresso, CPMD, CP2K, ABINT, CASTEP, DFTB+, and LAMPPS.
Combining the user forums for all of these programs into one stack exchange, there could be a lot of people asking about the modeling of the chemical physics of materials. Perhaps other chemical physics software such as CFOUR, MOLPRO, DIRAC, ORCA, MRCC, ADF, GAUSSIAN, PSI4, DALTON, and MOLCAS may also have their very active forum users start using Stack Exchange more and more.
So I wonder what people think is the reason why the Chemistry and Physics SEs have only 1 question each, with a materials tag plus a computational or theory tag, when there's tens of thousands of people asking questions on the forum for just one of the materials modeling software packages?
Is there a different stack exchange where such questions get asked more often (such as some sort of Engineering SE)? If there is not, I wonder if people here might consider giving input on what the questions should look like on a Materials Modeling SE: https://area51.stackexchange.com/proposals/122958/materials-modeling