We study the ultrafast time evolution of cyclobutanone excited to singlet n-->Rydberg state through XMS-CASPT2 nonadiabatic surface-hopping simulations. These dynamics predict relaxation to ground-state with a timescale of 822 +/- 45 fs with minimal involvement of triplets. The major relaxation path to the ground-state involves a three-state degeneracy region and leads to variety of fragmented photoproducts. We simulate the resulting time-resolved electron-diffraction spectra which track the relaxation of the excited state and the formation of various photoproducts in the ground-state.
Tough question... I'd say it's a tossup between "the" and "nonadiabatic."
Honorable mention to "Möller-Plesset second order perturbation theory" which had to be disqualified for not being a single word. Nonadiabatic squeaked in under the margin on this one, I had to convince my spellchecker that it was, in fact, a single word.
Nonadiabatic dynamics are quite cool. My PhD research was on ultra-fast light driven processes, so I spent quite a bit of time trying to understand those. I like that word too! 😁