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Durham University

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Publication details for Dr Basile Curchod

Mignolet, Benoit & Curchod, Basile F. E. (2019). Excited-State Molecular Dynamics Triggered by Light Pulses – Ab Initio Multiple Spawning vs Trajectory Surface Hopping. The Journal of Physical Chemistry A 123(16): 3582-3591.

Author(s) from Durham

Abstract

Trajectory surface hopping and ab initio multiple spawning are two commonly em
ployed methods for simulating the excited-state dynamics of molecules. Trajectory
surface hopping portrays the dynamics of nuclear wavepackets by a swarm of indepen
dent classical trajectories, which can hop between electronic states. Ab initio multiple
spawning, on the other hand, expresses nuclear wavepackets in a basis of traveling,
coupled basis functions, whose number can be extended in case of coupling between
electronic states. In the following, we propose to compare the performance of these
two methods to describe processes involving the explicit interaction of a molecule with
laser pulses. We base this comparison on the LiH molecule, as it is compatible with
numerically-exact simulations using quantum dynamics. As recognized in earlier works,
the limitations of TSH due to its inherent independent trajectory approximation are
further enhanced when studying an explicit photoexcitation. While ab initio multiple
spawning is also based on a series of approximations, the couplings between its trav
eling basis functions allow for a proper description of phenomena that TSH cannot
describe with its inherent independent trajectory approximation, even when applying
decoherence corrections. We show here for different in silico experiments involving
laser pulses that ab initio multiple spawning overcomes the limitations experienced by
trajectory surface hopping and offers an at least qualitative description of population
transfer between electronic states.