Assessment of excited-state molecular geometries with optimally-tuned range-separated hybrid functionals

Computational modelling of photochemical processes (e.g., for photocatalysis) requires accurate descriptions of excited-state structural dynamics of the involved molecules. Often, the starting point of such investigations are geometries optimized for the lowest-lying excited state, as obtained in time-dependent density functional theory (TD-DFT) or high-level wave-function methods. While calculations based on TD-DFT are computationally very efficient, they often do not reach the accuracy of computationally more expensive wave-function methods[1]. However, the recently developed class of optimally-tuned range-separated hybrid (OT-RSH) functionals promises to reduce the gap in accuracy[2].
Here, we assess the precision of excited-state geometries obtained with TD-DFT and OT-RSH for a selection of organic molecules. Our focus lies on structural parameters (e.g., bond lengths, bond angles, etc.) of the lowest-excited singlet states, which we compare to high accuracy wave-function data from literature to benchmark our results.

[1] C. Azarias, J. Phys. Chem. A, 121, 32, 6122 (2017)
[2] L. Kronik et al., J. Chem. Theory Comput., 8, 5, 1515 (2012)