Performance of Exchange-Correlation Functionals Based on Correlated Orbital Theory Conditions in Predicting Conjugated Polymer Bandgaps

Quantum Theory Project (QTP) functionals, which are based on Correlated Orbital Theory (COT) conditions, are compared to popular exchange-correlation (XC) functionals (B3LYP, PBE0, CAM-B3LYP, ωB97XD, and HSE06) for describing fundamental quantities of conducting polymers (PEDOT, polyfuran, and polythiophene). Thus, ωB97XD yields the best results for ionization potentials, with discrepancies ranging from −0.08 to 0.34 eV across polymers compared to reference data. However, QTP functionals are superior for electron affinities, with deviations between −0.10 and 0.26 eV for polyfuran and polythiophene. Consequently, ωB97XD and QTP functionals also provide the most accurate fundamental gap predictions, especially by CAM-QTP-00 and ωB97XD, with deviations from −0.47 to 0.85 eV for the same two polymers. Additionally, LC-QTP is the most successful XC functional for the lowest lying singlet to triplet excitation energies, with deviations between −0.52 and −0.27 eV. Hence, this study reinforces the promising performance of COT-based XC functionals for materials science applications.