  We unify two prevailing theories of thermal quenching (TQ) in
rare-earth-activated inorganic phosphors - the cross-over and auto-ionization
mechanisms - into a single predictive model. Crucially, we have developed
computable descriptors for activator environment stability from ab initio
molecular dynamics simulations to predict TQ under the cross-over mechanism,
which can be augmented by a band gap calculation to account for
auto-ionization. The resulting TQ model predicts the experimental TQ in 29
known phosphors to within ~ 3-8%. Finally, we have developed an efficient
topological approach to rapidly screen vast chemical spaces for the discovery
of novel, thermally robust phosphors.
