Electronic structure of norbornadiene and quadricyclane

Physical Chemistry Chemical Physics, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

The ground and excited state electronic structure of the molecular photoswitches quadricyclane norbornadiene is examined qualitatively quantitatively.

Language: Английский

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Spin–Orbit Coupling and Admixture Coefficients in SA-CASSCF and MS-CASPT2, and Triplet Excitation Yield Simulated via Trajectory Surface Hopping and Calibrated SA-CASSCF in 1,2-Dioxetane Derivatives

The Journal of Physical Chemistry A, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 26, 2025

The energy gaps, spin-orbit coupling (SOC), and admixture coefficients over a series of the configurations are evaluated by SA-CASSCF/6-31G, SA-CASSCF/6-31G*, SA-CASSCF/ANO-RCC-VDZP, MS-CASPT2/ANO-RCC-VDZP to reveal extent inaccuracy SA-CASSCF. By comparing mean absolute errors for gaps coefficient magnitudes (ACMs) measured between or SA-CASSCF/ANO-RCC-VDZP MS-CASPT2/ANO-RCC-VDZP, SA-CASSCF/6-31G is selected as electronic structure method in nonadiabatic molecular dynamics simulation. major components ACMs identified compared; we find that underestimated which verified reasonable triplet quantum yield simulated trajectory surface hopping calibrated SA-CASSCF/6-31G. magnitude singlet-triplet mixing positively correlates probability mixed singlet states, confirmed computed S-T transition probability.

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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Quantum Quality with Classical Cost: Ab Initio Nonadiabatic Dynamics Simulations Using the Mapping Approach to Surface Hopping

The Journal of Physical Chemistry Letters, Journal Year: 2024, Volume and Issue: 15(22), P. 5814 - 5823

Published: May 23, 2024

Nonadiabatic dynamics methods are an essential tool for investigating photochemical processes. In the context of employing first-principles electronic structure techniques, such simulations can be carried out in a practical manner using semiclassical trajectory-based or wave packet approaches. While all approaches applicable to necessarily approximate, it is commonly thought that offer inherent advantages over their counterparts terms accuracy and this trait simply comes at higher computational cost. Here we demonstrate mapping approach surface hopping (MASH), recently introduced nonadiabatic method, efficiently applied tandem with

Language: Английский

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Using a multistate mapping approach to surface hopping to predict the ultrafast electron diffraction signal of gas-phase cyclobutanone

The Journal of Chemical Physics, Journal Year: 2024, Volume and Issue: 160(20)

Published: May 28, 2024

Using the recently developed multistate mapping approach to surface hopping (multistate MASH) method combined with SA(3)-CASSCF(12,12)/aug-cc-pVDZ electronic structure calculations, gas-phase isotropic ultrafast electron diffraction (UED) of cyclobutanone is predicted and analyzed. After excitation into n-3s Rydberg state (S2), can relax through two S2/S1 conical intersections, one characterized by compression CO bond other dissociation α-CC bond. Subsequent transfer ground (S0) then achieved via additional S1/S0 intersections that lead three reaction pathways: α ring-opening, ethene/ketene production, liberation. The UED signal from MASH simulations, allowing for a direct comparison experimental data. This work, which contribution prediction challenge, facilitates identification main photoproducts in thereby emphasizes importance dynamics simulations interpretation experiments.

Language: Английский

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A size-consistent multi-state mapping approach to surface hopping

The Journal of Chemical Physics, Journal Year: 2024, Volume and Issue: 160(24)

Published: June 28, 2024

We develop a multi-state generalization of the recently proposed mapping approach to surface hopping (MASH) for simulation electronically nonadiabatic dynamics. This new extends original MASH method be able treat systems with more than two electronic states. It differs from previous approaches in that it is size consistent and rigorously recovers two-state appropriate limits. demonstrate accuracy by applying series model which exact benchmark results are available, we find well suited photochemical relaxation processes.

Language: Английский

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Simulation of Ultrafast Excited-State Dynamics in Fe(II) Complexes: Assessment of Electronic Structure Descriptions

Journal of Chemical Theory and Computation, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 3, 2025

The assessment of electronic structure descriptions utilized in the simulation ultrafast excited-state dynamics Fe(II) complexes is presented. Herein, we evaluate performance RPBE, OPBE, BLYP, B3LYP, B3LYP*, PBE0, TPSSh, CAM-B3LYP, and LC-BLYP (time-dependent) density functional theory (DFT/TD-DFT) methods full-dimensional trajectory surface hopping (TSH) simulations carried out on linear vibronic coupling (LVC) potentials. We exploit existence time-resolved X-ray emission spectroscopy (XES) data for [Fe(bmip)2]2+ [Fe(terpy)2]2+ prototypes between metal-to-ligand charge-transfer (MLCT) metal-centered (MC) states, which serve as a reference to benchmark calculations (bmip = 2,6-bis(3-methyl-imidazole-1-ylidine)-pyridine, terpy 2,2′:6′,2″-terpyridine). results show that simulated population MLCT MC states with various spin multiplicities (singlet, triplet, quintet) highly depend DFT/TD-DFT method, percentage exact (Hartree–Fock) exchange being governing factor. Importantly, B3LYP* TPSSh are only satisfactory performance, best reproducing experimentally resolved both complexes, signaling an optimal balance description MLCT–MC energetics. This work demonstrates power combining TSH/LVC experimental potential energy surfaces.

Language: Английский

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Numerically stable resonating Hartree–Fock

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(10)

Published: March 12, 2025

The simulation of excited states at low computational cost remains an open challenge for electronic structure (ES) methods. While much attention has been given to orthogonal ES methods, relatively little work done develop nonorthogonal methods states, particularly those involving orbital optimization. We present here a numerically stable formulation the Resonating Hartree–Fock (ResHF) method that uses matrix adjugate remove numerical instabilities arising from nearly orbitals, and as result, we demonstrate improvements ResHF wavefunction then benchmark performance against complete active space self-consistent field in avoided crossing LiF, torsional rotation ethene, singlet–triplet energy gaps selection small molecules. is promising state because it incorporates relaxation state-specific while retaining correct crossings state-averaged approaches. Our open-source implementation, yucca, available on GitLab.

Language: Английский

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Assessing the performance of coupled-trajectory schemes on full-dimensional two-state linear vibronic coupling models

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(10)

Published: March 14, 2025

We investigate the performance of coupled-trajectory methods for nonadiabatic molecular dynamics in simulating photodynamics 4-(dimethylamino)benzonitrile (DMABN) and fulvene, with electronic structure provided by linear vibrational coupling models. focus on mixed quantum-classical (CTMQC) algorithm (combined) Tully surface hopping [(C)CTTSH] comparison to independent-trajectory approaches, such as multi-trajectory Ehrenfest hopping. Our analysis includes not only populations but also additional nuclear properties position momentum space. For both DMABN recently developed CCTTSH successfully resolves internal inconsistencies Instead, we find that highlights a significant weakness CTMQC, which arises when trajectories remain long time vicinity region strong nonadiabaticity.

Language: Английский

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Generalized Velocity Sampling at a Transition State and Nonadiabatic Dynamics of Four-Membered Heterocyclic Peroxides

The Journal of Physical Chemistry Letters, Journal Year: 2025, Volume and Issue: unknown, P. 3473 - 3482

Published: March 29, 2025

We propose the generalized initial velocity sampling algorithm at a transition state, in which total kinetic energy and extra positive along reaction coordinate have been introduced to improve accuracy efficiency of nonadiabatic dynamics simulation. This is very useful for chemical reactions with multiple states, e.g., two states thermolysis four-membered heterocyclic peroxides. The dependence chemiexcitation yields, dissociation times, other quantities on has investigated. By taking different CASPT2 corrections additional velocities into account, we found that resulting triplet quantum yield matches experimental result perfectly. In most ensembles, secondary primary intersystem crossing, i.e., first singlet excited state major direct production channel product trajectories.

Language: Английский

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