Spatial and temporal control of populations, branching ratios, and electronic coherences in LiH by a single one-cycle infrared pulse

Nikodem, Astrid; Levine, R. D.; Remacle, Françoise

doi:10.1103/physreva.95.053404

Cited by 31 publications

(26 citation statements)

References 76 publications

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“…5). 54,79,80 A first ultrashort UV pump pulse is sent on the molecule ('A' in the inset of Fig. 5), promoting part of the nuclear population from S 0 to S 1 .…”

mentioning

confidence: 99%

Excited-State Molecular Dynamics Triggered by Light Pulses—Ab Initio Multiple Spawning vs Trajectory Surface Hopping

Mignolet

Curchod

2019

J. Phys. Chem. A

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Trajectory surface hopping and ab initio multiple spawning are two commonly employed methods for simulating the excited-state dynamics of molecules. Trajectory surface hopping portrays the dynamics of nuclear wavepackets by a swarm of independent 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 traveling 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.

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“…5). 54,79,80 A first ultrashort UV pump pulse is sent on the molecule ('A' in the inset of Fig. 5), promoting part of the nuclear population from S 0 to S 1 .…”

mentioning

confidence: 99%

Excited-State Molecular Dynamics Triggered by Light Pulses—Ab Initio Multiple Spawning vs Trajectory Surface Hopping

Mignolet

Curchod

2019

J. Phys. Chem. A

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“…It is suggested that the coupling of this electronic motion to the nuclear motion on the femtosecond time scale may control the fragmentation patterns (charge-directed reactivity). Similar effects should be present in neutral systems, with ionization replaced by coherent excitation of several electronic states [34][35][36][37][38][39][40]. While in ionization one talks about the dynamics of a hole [41] and its coupling to nuclear degrees of freedom, in a neutral system one can talk about the coupling between the exciton and the nuclei [42].…”

Section: Introductionmentioning

confidence: 90%

On the preservation of coherence in the electronic wavepacket of a neutral and rigid polyatomic molecule

Csehi,

Badankó,

Halász

et al. 2020

Preprint

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We present various types of reduced models including five vibrational modes and three electronic states for the pyrazine molecule in order to investigate the lifetime of electronic coherence in a rigid and neutral system. Using an ultrafast optical pumping in the ground state (1 1 Ag), we prepare a coherent superposition of two bright excited states, 1 1 B2u and 1 1 B1u, and reveal the effect of the nuclear motion on the preservation of the electronic coherence induced by the laser pulse. More specifically, two aspects are considered: the anharmonicity of the potential energy surfaces and the dependence of the transition dipole moments (TDMs) with respect to the nuclear coordinates. To this end, we define an ideal model by making three approximations: (i) only the five totally symmetric modes move, (ii) which correspond to uncoupled harmonic oscillators, and (iii) the TDMs from the ground electronic state to the two bright states are constant (Franck-Condon approximation). We then lift the second and third approximations by considering, first, the effect of anharmonicity, second, the effect of coordinate-dependence of the TDMs (first-order Herzberg-Teller contribution), third, both. Our detailed numerical study with quantum dynamics confirms long-term revivals of the electronic coherence even for the most realistic model.

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“…evolution) of the pulse and can affect the dynamics 88,89 as well as the branching ratio. 90 The first pulse is centered at the time t 0 while the probe pulse is a replica of the pump and is centered at the pump-probe delay time t PP .…”

Section: Iiib Computational Detailsmentioning

confidence: 99%

A walk through the approximations of ab initio multiple spawning

Mignolet

Curchod

2018

The Journal of Chemical Physics

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Full multiple spawning offers an in principle exact framework for excited-state dynamics, where nuclear wavefunctions in different electronic states are represented by a set of coupled trajectory basis functions that follow classical trajectories. The couplings between trajectory basis functions can be approximated to treat molecular systems, leading to the ab initio multiple spawning method which has been successfully employed to study the photochemistry and photophysics of several molecules. However, a detailed investigation of its approximations and their consequences is currently missing in the literature. In this work, we simulate the explicit photoexcitation and subsequent excited-state dynamics of a simple system, LiH, and we analyze (i) the effect of the ab initio multiple spawning approximations on different observables and (ii) the convergence of the ab initio multiple spawning results towards numerically exact quantum dynamics upon a progressive relaxation of these approximations. We show that, despite the crude character of the approximations underlying ab initio multiple spawning for this low-dimensional system, the qualitative excited-state dynamics is adequately captured, and affordable corrections can further be applied to ameliorate the coupling between trajectory basis functions.

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Spatial and temporal control of populations, branching ratios, and electronic coherences in LiH by a single one-cycle infrared pulse

Cited by 31 publications

References 76 publications

Excited-State Molecular Dynamics Triggered by Light Pulses—Ab Initio Multiple Spawning vs Trajectory Surface Hopping

Excited-State Molecular Dynamics Triggered by Light Pulses—Ab Initio Multiple Spawning vs Trajectory Surface Hopping

On the preservation of coherence in the electronic wavepacket of a neutral and rigid polyatomic molecule

A walk through the approximations of ab initio multiple spawning

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