posted on 2023-04-25, 17:04authored byAddison
K. Bralick, Erica C. Mitchell, Anna C. Doner, Annabelle R. Webb, Matthew G. Christianson, Justin M. Turney, Brandon Rotavera, Henry F. Schaefer
Vacuum UV absorption spectroscopy is regularly used to
provide
unambiguous identification of a target species, insight into the electronic
structure of molecules, and quantitative species concentrations. As
molecules of interest have become more complex, theoretical spectra
have been used in tandem with laboratory spectroscopic analysis or
as a replacement when experimental data is unavailable. However, it
is difficult to determine which theoretical methodologies can best
simulate experiment. This study examined the performance of EOM-CCSD
and 10 TD-DFT functionals (B3LYP, BH&HLYP, BMK, CAM-B3LYP, HSE,
M06-2X, M11, PBE0, ωB97X-D, and X3LYP) to produce reliable vacuum
UV absorption spectra for 19 small oxygenates and hydrocarbons using
vertical excitation energies. The simulated spectra were analyzed
against experiment using both a qualitative analysis and quantitative
metrics, including cosine similarity, relative integral change, mean
signed error, and mean absolute error. Based on our ranking system,
it was determined that M06-2X was consistently the top performing
TD-DFT method with BMK, CAM-B3LYP, and ωB97X-D also producing
reliable spectra for these small combustion species.