Both pure TD-DFT and TDA were used but the differences between the two methods will be shown later to be small (< 0.05 eV). The emitter was treated fully quantum mechanically, whereas host molecules within 8 Å of the guest were included as point charges with the charges being the same as the ones used in the MD simulations. Basis sets and exchange correlation functionals were kept consistent with the force field parameterisation step. Example QM input files are provided in the Supporting Data.