  Photo-ionization induced ultrafast electron dynamics is considered as a
precursor to the slower nuclear dynamics associated with molecular
dissociation. Here, using ab initio multielectron wave-packet propagation
method, we study the overall many-electron dynamics, triggered by the
ionization of outer-valence orbitals of different tautomers of a prototype
molecule with more than one symmetry element. From the time evolution of the
initially created averaged hole density of each system, we identify distinctly
different charge dynamics response in the tautomers. We observe that keto form
shows charge migration direction away from the nitrogen bonded with tautomeric
hydrogen, while in enol - away from oxygen bonded to tautomeric hydrogen.
Additionally, the dynamics following ionization of molecular orbitals of
different symmetry reveal that a' orbitals show fast and highly delocalized
charge in comparison to a" symmetry. These observations indicate why different
tautomers respond differently to an XUV ionization, and might explain the
subsequent different fragmentation pathways. An experimental schematics
allowing detection and reconstruction of such charge dynamics is also proposed.
Although the present study uses a simple, prototypical bio-relevant molecule,
it reveals the explicit role of molecular symmetry and tautomerism in the
ionization-triggered charge migration that controls many ultrafast physical,
chemical, and biological processes, making tautomeric forms a promising tool of
molecular design for desired charge migration.
