Predictive accuracy of ab initio photochemical quantum yields
In plain words
A photochemical quantum yield is the fraction of absorbed photons that produce a given product. Current simulations cannot yet predict these fractions reliably before an experiment is done.
Precise statement
For benchmark photoreactions (cyclobutanone photodissociation at 200 nm, azobenzene trans-cis isomerization, retinal isomerization in rhodopsin), predict product branching ratios and quantum yields to within 0.1 absolute, and ultrafast electron diffraction or photoelectron signals within experimental error, using electronic structure and nuclear dynamics without fitting to the target data. An answer is a protocol (electronic structure level plus dynamics method) shown to meet this accuracy in blind tests.
What would settle it
Blind prediction challenges in which simulations are submitted before ultrafast measurements are released.
Status in the literature
Unverified note
A 2024 blind prediction challenge on cyclobutanone photodissociation (J. Chem. Phys. collection, for example Suchan et al., https://doi.org/10.1063/5.0198333), compared with ultrafast electron diffraction data, showed a wide spread among methods.