Comparative study of TDDFT and TDDFT-based STEOM-DLPNO-CCSD calculations for predicting the excited-state properties of MR-TADF
Sunwoo Kang, Taekyung Kim
Abstract
The time dependent density functional theory (TDDFT) and TDDFT/similarity transformed EOM domain-based local pair natural orbital CCSD (STEOM-DLPNO-CCSD) calculations were explored to estimate their validity in predicting the excited-state properties of multi-resonant thermally activated delayed fluorescence (MR-TADF) materials. Obviously, it was demonstrated that TDDFT calculation is inadequate to provide the quantitative prediction of the lowest singlet excited-state (S 1 ), the lowest triplet excited-state (T 1 ), and ΔE ST . On the other hand, TDDFT/STEOM-DNLPNO-CCSD calculation reveals the superior prediction of S 1 , T 1 , and ΔE ST that are in quantitative agreement with experiments. More importantly, it was found that TD-LC- HPBE/STEOM-DLPNO-CCSD calculation provides the most accurate prediction of S 1 , T 1 , and ΔE ST . Accordingly, we suggest that TD-LC- HPBE/STEOM-DLPNO-CCSD calculation should be utilized to compute the excited-states properties of MR-TADF materials accurately.