Dynamics of FHCl Including Two Bidirectional Dissociation Channels: Comparative Study Using Quantum Nuclear Wavepackets and Semiclassical Trajectory Surface Hopping

The dynamics starting from the charge
transfer excited
state of
neutral FHCl includes two bidirectional dissociation channels, producing
“FH” and “Cl” fragments or “F”
and “HCl” fragments by electron-transfer (ET) or proton-transfer
(PT) processes, respectively. The quantum features of its dynamics
were studied using the quantum dynamics of nuclear wavepacket propagation
and the semiclassical dynamics of trajectory surface hopping propagation.
The MS-CASPT2(17,11)/aug-cc-pVTZ method was used for calculating the
energies of electronic states. Two critical quantum features identified
in previous studies were the dominance of PT over ET and the ∼80
fs time gap between the onset of the earlier PT and the later ET processes.
These features, in contrast to classical anticipation, were confirmed
again, and their classical interpretations were developed based on
the results of semiclassical dynamics. The relative location of nonadiabatic
regions with respect to the starting point of dynamics and the activation
of angular motion altering the HFCl angle play crucial roles in governing
the two quantum features.