The Mapping Approach to Surface Hopping (MASH) method, developed in the
group, has emerged as an alternative to the fewest-switches surface
hopping (FSSH) method. In this work, we assess the accuracy of the MASH
method in electronic coherences prediction. These quantities are key to
the study of Conical Intersections through novel X-ray spectroscopies,
such as the transient redistribution of ultrafast electronic coherences
in attosecond Raman signals (TRUECARS).
A new instanton method is developed to treat branch-point singularities of the flux correlation function and calculate rate constants. The new method predicts a huge 27 orders of magnitude tunnelling factor for the decay of singlet oxygen in water and shows excellent agreement with the large temperature-dependent kinetic isotope effects.
Tunnelling speeds up the reactions, but the geometric phase effect slows them down again. This recent project in the group was covered in Chemistry World.