(I'm a high energy theorist)Can you point me to a source/plot of an absorption spectrum or better projected density of states for a scintillator (ideally TlBr or NaI or CsI) that has a regular DFT prediction curve superimposed with the full GW excitonic picture and shows that above a certain energy the two predictions are essentially coincident? Alternatively, is there an authoritative source that states this and quantifies the energy threshold? Something like "typically (free and continuous spectrum) excitons sensibly change the density of states within a few meV above the band gap edge" or similar?
Hope you can help!