Prediction Challenge: Simulating Rydberg photoexcited cyclobutanone with surface hopping dynamics based on different electronic structure methods

The Journal of Chemical Physics, Journal Year: 2024, Volume and Issue: 160(15)

Published: April 16, 2024

This research examines the nonadiabatic dynamics of cyclobutanone after excitation into n → 3s Rydberg S2 state. It stems from our contribution to Special Topic Journal Chemical Physics test predictive capability computational chemistry against unseen experimental data. Decoherence-corrected fewest-switches surface hopping was used simulate with full and approximated couplings. Several simulation sets were computed different electronic structure methods, including a multiconfigurational wavefunction [multiconfigurational self-consistent field (MCSCF)] specially built describe dissociative channels, multireference semiempirical approach, time-dependent density functional theory, algebraic diagrammatic construction, coupled cluster. MCSCF predicts slow deactivation state (10 ps), followed by an ultrafast population transfer S1 S0 (<100 fs). CO elimination (C3 channel) dominates over C2H4 formation (C2 channel). These findings radically differ other which predicted lifetimes 10-250 times shorter C2 channel predominance. results suggest that routine methods may hold low power for outcome dynamics.

Language: Английский

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Photoexcited dynamics of the valence states of norbornadiene

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(9)

Published: March 3, 2025

The non-radiative decay of photoexcited norbornadiene, which together with its isomer quadricyclane forms a molecular photoswitch, is investigated using surface-hopping non-adiabatic dynamics. simulations are performed four levels electronic structure theory: CASSCF(2,2), CASSCF(4,4), XMS-CASPT2(2,2), and XMS-CASPT2(4,4). These models yield two distinct classes excited-state reaction pathways, different quantum yields for the isomerization. This illustrates significance potential energy surfaces when simulating nature pathways related to topographical features on surfaces, suggesting “design rules” chemical modification via substituent groups. How molecule approaches conical intersection also shown play decisive role in outcome.

Language: Английский

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Imaging the photochemical dynamics of cyclobutanone with MeV ultrafast electron diffraction

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(18)

Published: May 8, 2025

We study the photoinduced chemical dynamics of cyclobutanone upon excitation at 200 nm to 3s Rydberg state using MeV ultrafast electron diffraction (UED). observe both elastic scattering signal, which contains information about structural dynamics, and inelastic encodes electronic state. Our results suggest a sub-picosecond timescale for photodissociation an excited lifetime 230 femtoseconds. The dissociation is found be dominated by C3 channel, where cyclopropane CO are produced. branching ratio channel C2 ethene ketene produced, estimated ∼5:3. data that channels account ∼80% photoproducts, with remaining 20% exhibiting ring-opened structures. It associated process in shorter compared channel. Leveraging enhanced temporal resolution UED, our provide real-time mapping nuclear wave packet capturing complete photochemical from S2 minimum through S1/S0 conical intersection finally dissociation. experimental new insights into Norrish type I reaction can used benchmark non-adiabatic simulations.

Language: Английский

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Imaging the photochemistry of cyclobutanone using ultrafast electron diffraction: Experimental results

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(18)

Published: May 12, 2025

We investigated the ultrafast structural dynamics of cyclobutanone following photoexcitation at λ = 200 nm using gas-phase megaelectronvolt electron diffraction. Our investigation complements simulation studies same process within this special issue. It provides information about both electronic state population and through well-separable inelastic elastic scattering signatures. observe depopulation photoexcited S2 with n3s Rydberg character its signature a time constant (0.29 ± 0.2) ps toward S1 state. The undergoes ring-opening via Norrish Type-I reaction, likely while passing conical intersection S0. corresponding changes can be tracked by These appear delay (0.14 0.05) respect to initial photoexcitation, which is less than constant. This behavior evidence for ballistic nature once reached. resulting biradical species react further (1.2 two rival fragmentation channels yielding ketene ethylene, or propene carbon monoxide. study showcases value diffraction as an experimental benchmark nonadiabatic methods limits in interpretation such data without comparison simulations.

Language: Английский

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The photochemistry of Rydberg-excited cyclobutanone: Photoinduced processes and ground state dynamics

The Journal of Chemical Physics, Journal Year: 2024, Volume and Issue: 160(15)

Published: April 15, 2024

Owing to ring strain, cyclic ketones exhibit complex excited state dynamics with multiple competing photochemical channels active on the ultrafast timescale. While of cyclobutanone after π* ← n excitation into lowest-energy singlet (S1) has been extensively studied, following 3s higher-lying Rydberg (S2) are less well understood. Herein, we employ fully quantum multiconfigurational time-dependent Hartree (MCTDH) simulations using a model Hamiltonian as "on-the-fly" trajectory-based surface-hopping (TSHD) study relaxation and predict electron diffraction scattering signature these dynamics. Our MCTDH TSHD indicate that from initially-populated occurs timescale few hundreds femtoseconds picosecond, consistent symmetry-forbidden nature state-to-state transition involved. There is no obvious involvement triplet states within timeframe our (<2 ps). After non-radiative electronic ground (S0), vibrationally hot sufficient internal energy form fragmented products including C2H4 + CH2CO (C2; 20%) C3H6 CO (C3; 2.5%). We discuss limitations simulations, how may influence observe, and-ultimately-the predictive power simulated experimental observable.

Language: Английский

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Simulating ultrafast transient absorption spectra from first principles using a time-dependent configuration interaction probe

The Journal of Chemical Physics, Journal Year: 2024, Volume and Issue: 161(4)

Published: July 23, 2024

Transient absorption spectroscopy (TAS) is among the most common ultrafast photochemical experiments, but its interpretation remains challenging. In this work, we present an efficient and robust method for simulating TAS signals from first principles. Excited-state stimulated emission (SE) are computed using time-dependent complete active space configuration interaction (TD-CASCI) simulations, leveraging robustness of time-domain simulation to minimize electronic structure failure. We demonstrate our approach by signal 1′-hydroxy-2′-acetonapthone (HAN) ab initio multiple spawning nonadiabatic molecular dynamics simulations. Our results compared gas-phase data recorded both jet-cooled (T ∼ 40 K) hot (∼403 molecules via cavity-enhanced (CE-TAS). Decomposition spectrum allows us assign a rise in SE excited-state proton transfer ultimate decay relaxation through twisted conical intersection. The total cost computing observable (∼1700 graphics processing unit hours ∼4 ns electron dynamics) was markedly less than that performing calculations used compute underlying dynamics.

Language: Английский

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An Exhaustive Quantum-Classical Study of C₆F₆⁺ Using the Newly Formulated Parallel TDDVR Method

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: 128(28), P. 5777 - 5795

Published: July 9, 2024

We recently implemented our parallelized quantum-classical dynamical approach, known as the Time-Dependent Discrete Variable Representation (TDDVR) method, which is applied to spectroscopically important hexafluorobenzene (HFBz) radical cation, where several conical intersections exist in their seven lowest excited electronic states (S

Language: Английский

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