TD-DFT calculations of one- and two-photon absorption in Coumarin C153 and Prodan: attuning theory to experiment


Merle Uudsemaa, Aleksander Trummal, Sophie de Reguardati, Patrik R. Callis, Aleksander Rebane


Physical Chemistry Chemical Physics


We use TD-DFT to calculate the one-photon absorption (1PA) and two-photon absorption (2PA) properties of C153 and Prodan in toluene and DMSO, and benchmark different methods relative to accurate experimental data available from the literature on these particular systems. As the first step, we modify the range-separated TD-DFT to provide the best prediction for the peak 1PA wavelength, and then apply the optimized functionals to achieve quantitative predictions of the corresponding two-photon absorption cross section, ?2PA, with an accuracy ?10-20% in C153 and ?20-30% in Prodan. To elucidate the origin of residual discrepancies between the theory and experimental observations, we invoked the two essential states model for ?2PA, which allows us to verify not only the transition wavelength and the ?2PA value, but also to quantitatively benchmark the calculation of key molecular parameters such as the transition dipole moment and the change of the permanent dipole moment. Such comprehensive cross-checking indicates that a larger discrepancy in Prodan is most likely caused by a noted failure of DFT to predict the relative intensity and relative ordering of closely lying excited states with different degrees of intramolecular charge transfer, which we further support by analyzing the predictions obtained by high-level coupled-cluster calculations in the gas phase. Our results highlight the utility of benchmarking the calculations not only relative to other theoretical methods, but also in comparison to the experimental measurements, wherever such data are available.



How is this information collected?

This collection of Montana State authored publications is collected by the Library to highlight the achievements of Montana State researchers and more fully understand the research output of the University. They use a number of resources to pull together as complete a list as possible and understand that there may be publications that are missed. If you note the omission of a current publication or want to know more about the collection and display of this information email Leila Sterman.