Currently there are 131 questions with the tag
eigenvalues. This includes both questions around the finding of eigenvalues and eigenvectors of a matrix as well as of a differential operator (and associated eigenfunctions).
As someone who is interested in questions of the latter type but not of the former, I'd like to split the tag into the two parts. I'd suggest
eigenfunctions personally, but open to suggestions (or telling that the tag shouldn't be split).