Accelerated Computer-Aided\nScreening of Optical Materials:\nInvestigating the Potential of Δ‑SCF Methods to Predict\nEmission Maxima of Large Dye Molecules

Accurate simulation of electronic excited states of large\nchromophores\nis often difficult due to the computationally expensive nature of\nexisting methods. Common approximations such as fragmentation methods\nthat are routinely applied to ground-state calculations of large molecules\nare not easily applicable to excited states due to the delocalized\nnature of electronic excitations in most practical chromophores. Thus,\nspecial techniques specific to excited states are needed. Δ-SCF\nmethods are one such approximation that treats excited states in a\nmanner analogous to that for ground-state calculations, accelerating\nthe simulation of excited states. In this work, we employed the popular\ninitial maximum overlap method (IMOM) to avoid the variational collapse\nof the electronic excited state orbitals to the ground state. We demonstrate\nthat it is possible to obtain emission energies from the first singlet\n(S<sub>1</sub>) excited state of many thousands of dye molecules without\nany external intervention. Spin correction was found to be necessary\nto obtain accurate excitation and emission energies. Using thousands\nof dye-like chromophores and various solvents (12,318 combinations),\nwe show that the spin-corrected initial maximum overlap method accurately\npredicts emission maxima with a mean absolute error of only 0.27 eV.\nWe further improved the predictive accuracy using linear fit-based\ncorrections from individual dye classes to achieve an impressive performance\nof 0.17 eV. Additionally, we demonstrate that IMOM spin density can\nbe used to identify the dye class of chromophores, enabling improved\nprediction accuracy for complex dye molecules, such as dyads (chromophores\ncontaining moieties from two different dye classes). Finally, the\nconvergence behavior of IMOM excited state SCF calculations is analyzed\nbriefly to identify the chemical space, where IMOM is more likely\nto fail.