1
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Dey D, Woodhouse JL, Taylor MP, Fielding HH, Worth GA. On the multiphoton ionisation photoelectron spectra of phenol. Phys Chem Chem Phys 2024; 26:3451-3461. [PMID: 38205824 DOI: 10.1039/d3cp05559k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
The phenol molecule is a prototype for non-adiabatic dynamics and the excited-state photochemistry of biomolecules. In this article, we report a joint theoretical and experimental investigation on the resonance enhanced multiphoton ionisation photoelectron (REMPI) spectra of the two lowest ionisation bands of phenol. The focus is on the theoretical interpretation of the measured spectra using quantum dynamics simulations. These were performed by numerically solving the time-dependent Schrödinger equation using the multi-layer variant of the multiconfiguration time-dependent Hartree algorithm together with a vibronic coupling Hamiltonian model. The ionising laser pulse is modelled explicitly within the ionisation continuum model to simulate experimental femtosecond 1+1 REMPI photoelectron spectra. These measured spectra are sensitive to very short lived electronically excited states, providing a rigorous benchmark for our theoretical methods. The match between experiment and theory allows for an interpretation of the features of the spectra at different wavelengths and shows that there are features due to both 'direct' and 'indirect' ionisation, resulting from non-resonant and resonant excitation by the pump pulse.
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Affiliation(s)
- Diptesh Dey
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Joanne L Woodhouse
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
- Department of Chemistry, University of Southampton, Southampton, SO17 1BJ, UK
| | - Marcus P Taylor
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Helen H Fielding
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Graham A Worth
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
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2
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Martín Santa Daría A, González-Sánchez L, Gómez S. Coronene: a model for ultrafast dynamics in graphene nanoflakes and PAHs. Phys Chem Chem Phys 2023; 26:174-184. [PMID: 37811951 DOI: 10.1039/d3cp03656a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Assuming a delta pulse excitation, quantum wavepackets are propagated on the excited state manifold in the energy range from 3.4-5.0 eV for coronene and 2.4-3.5 eV for circumcoronene to study the time evolution of the states as well as their lifetimes. The full-dimensional (102 and 210 degrees of freedom for coronene and circumcoronene respectively) non-adiabatic dynamics simulated with the ML-MCTDH method on twelve coupled singlet electronic states show that the different absorption spectra are only due to electronic delocalisation effects that change the excited state energies, but the structural dynamics in both compounds are identical. Breathing and tilting motions drive the decay dynamics of the electronic states away from the Frank-Condon region independently of the size of the aromatic system. This promising result allows the use of coronene as a model system for the dynamics of larger polycyclic aromatic hydrocarbons (PAHs) and graphene one dimensional sheets or nanoflakes.
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Affiliation(s)
| | | | - Sandra Gómez
- Departamento de Química Física, Universidad de Salamanca, Spain.
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3
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Klētnieks Ē, Alonso YC, Vaníček JJL. Isotope Effects on the Electronic Spectra of Ammonia from Ab Initio Semiclassical Dynamics. J Phys Chem A 2023; 127:8117-8125. [PMID: 37738161 PMCID: PMC10561269 DOI: 10.1021/acs.jpca.3c04607] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 08/22/2023] [Indexed: 09/24/2023]
Abstract
Despite its simplicity, the single-trajectory thawed Gaussian approximation has proven useful for calculating the vibrationally resolved electronic spectra of molecules with weakly anharmonic potential energy surfaces. Here, we show that the thawed Gaussian approximation can capture surprisingly well even more subtle observables, such as the isotope effects in the absorption spectra, and we demonstrate it on the four isotopologues of ammonia (NH3, NDH2, ND2H, and ND3). The differences in their computed spectra are due to the differences in the semiclassical trajectories followed by the four isotopologues, and the isotope effects─narrowing of the transition band and reduction of the peak spacing─are accurately described by this semiclassical method. In contrast, the adiabatic harmonic model shows a double progression instead of the single progression seen in the experimental spectra. The vertical harmonic model correctly shows only a single progression but fails to describe the anharmonic peak spacing. Analysis of the normal-mode activation upon excitation provides insight into the elusiveness of the symmetric stretching progression in the spectra.
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Affiliation(s)
- Ēriks Klētnieks
- Laboratory of Theoretical Physical
Chemistry, Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne
(EPFL), Lausanne CH-1015, Switzerland
| | - Yannick Calvino Alonso
- Laboratory of Theoretical Physical
Chemistry, Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne
(EPFL), Lausanne CH-1015, Switzerland
| | - Jiří J. L. Vaníček
- Laboratory of Theoretical Physical
Chemistry, Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne
(EPFL), Lausanne CH-1015, Switzerland
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4
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Segatta F, Ruiz DA, Aleotti F, Yaghoubi M, Mukamel S, Garavelli M, Santoro F, Nenov A. Nonlinear Molecular Electronic Spectroscopy via MCTDH Quantum Dynamics: From Exact to Approximate Expressions. J Chem Theory Comput 2023; 19:2075-2091. [PMID: 36961952 PMCID: PMC10100531 DOI: 10.1021/acs.jctc.2c01059] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2023]
Abstract
We present an accurate and efficient approach to computing the linear and nonlinear optical spectroscopy of a closed quantum system subject to impulsive interactions with an incident electromagnetic field. It incorporates the effect of ultrafast nonadiabatic dynamics by means of explicit numerical propagation of the nuclear wave packet. The fundamental expressions for the evaluation of first- and higher-order response functions are recast in a general form that can be used with any quantum dynamics code capable of computing the overlap of nuclear wave packets evolving in different states. Here we present the evaluation of these expressions with the multiconfiguration time-dependent Hartree (MCTDH) method. Application is made to pyrene, excited to its lowest bright excited state S2 which exhibits a sub-100-fs nonadiabatic decay to a dark state S1. The system is described by a linear vibronic coupling Hamiltonian, parametrized with multiconfiguration electronic structure methods. We show that the ultrafast nonadiabatic dynamics can have a remarkable effect on the spectral line shapes that goes beyond simple lifetime broadening. Furthermore, a widely employed approximate expression based on the time scale separation of dephasing and population relaxation is recast in the same theoretical framework. Application to pyrene shows the range of validity of such approximations.
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Affiliation(s)
- Francesco Segatta
- Dipartimento di Chimica Industriale "Toso Montanari", University of Bologna, Viale del Risorgimento, 4, 40136 Bologna, Italy
| | - Daniel Aranda Ruiz
- ICMol, Universidad de Valencia, Catedrático José Beltrán Martínez, 2, 46980 Paterna, Spain
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area della Ricerca del CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Flavia Aleotti
- Dipartimento di Chimica Industriale "Toso Montanari", University of Bologna, Viale del Risorgimento, 4, 40136 Bologna, Italy
| | - Martha Yaghoubi
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area della Ricerca del CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Shaul Mukamel
- Department of Chemistry and Department of Physics and Astronomy, University of California, Irvine, California 92697, United States
| | - Marco Garavelli
- Dipartimento di Chimica Industriale "Toso Montanari", University of Bologna, Viale del Risorgimento, 4, 40136 Bologna, Italy
| | - Fabrizio Santoro
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area della Ricerca del CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Artur Nenov
- Dipartimento di Chimica Industriale "Toso Montanari", University of Bologna, Viale del Risorgimento, 4, 40136 Bologna, Italy
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5
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Penfold TJ, Eng J. Mind the GAP: quantifying the breakdown of the linear vibronic coupling Hamiltonian. Phys Chem Chem Phys 2023; 25:7195-7204. [PMID: 36820783 DOI: 10.1039/d2cp05576g] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Excited state dynamics play a critical role across a broad range of scientific fields. Importantly, the highly non-equilibrium nature of the states generated by photoexcitation means that excited state simulations should usually include an accurate description of the coupled electronic-nuclear motion, which often requires solving the time-dependent Schrödinger equation (TDSE). One of the biggest challenges for these simulations is the requirement to calculate the PES over which the nuclei evolve. An effective approach for addressing this challenge is to use the approximate linear vibronic coupling (LVC) Hamiltonian, which enables a model potential to be parameterised using relatively few quantum chemistry calculations. However, this approach is only valid provided there are no large amplitude motions in the excited state dynamics. In this paper we introduce and deploy a metric, the global anharmonicity parameter (GAP), which can be used to assess the accuracy of an LVC potential. Following its derivation, we illustrate its utility by applying it to three molecules exhibiting different rigidity in their excited states.
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Affiliation(s)
- Thomas J Penfold
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Julien Eng
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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6
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Malde R, Parkes MA, Staniforth M, Woolley JM, Stavros VG, Chudasama V, Fielding HH, Baker JR. Intramolecular thiomaleimide [2 + 2] photocycloadditions: stereoselective control for disulfide stapling and observation of excited state intermediates by transient absorption spectroscopy. Chem Sci 2022; 13:2909-2918. [PMID: 35382459 PMCID: PMC8905992 DOI: 10.1039/d1sc06804k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 01/16/2022] [Indexed: 11/21/2022] Open
Abstract
Thiomaleimides undergo efficient intermolecular [2 + 2] photocycloaddition reactions and offer applications from photochemical peptide stapling to polymer crosslinking; however, the reactions are limited to the formation of the exo head-to-head isomers. Herein, we present an intramolecular variation which completely reverses the stereochemical outcome of this photoreaction, quantitatively generating endo adducts which minimise the structural disturbance of the disulfide staple and afford a 10-fold increase in quantum yield. We demonstrate the application of this reaction on a protein scaffold, using light to confer thiol stability to an antibody fragment conjugate. To understand more about this intriguing class of [2 + 2] photocycloadditions, we have used transient absorption spectroscopy (electronic and vibrational) to study the excited states involved. The initially formed S2 (π1π*) excited state is observed to decay to the S1 (n1π*) state before intersystem crossing to a triplet state. An accelerated intramolecular C–C bond formation provides evidence to explain the increased efficiency of the reaction, and the impact of the various excited states on the carbonyl vibrational modes is discussed. Tethered bromomaleimides are described which undergo thiol conjugation and rapid regio- and stereoselective photocycloadditions to serve as disulfide staples; with the excited state intermediates observed by transient absorption spectroscopies.![]()
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Affiliation(s)
- Roshni Malde
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Michael A. Parkes
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Michael Staniforth
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Jack M. Woolley
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Vasilios G. Stavros
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Vijay Chudasama
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Helen H. Fielding
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - James R. Baker
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
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7
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Zobel JP, Heindl M, Plasser F, Mai S, González L. Surface Hopping Dynamics on Vibronic Coupling Models. Acc Chem Res 2021; 54:3760-3771. [PMID: 34570472 PMCID: PMC8529708 DOI: 10.1021/acs.accounts.1c00485] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The simulation of photoinduced non-adiabatic dynamics is of great
relevance in many scientific disciplines, ranging from physics and
materials science to chemistry and biology. Upon light irradiation,
different relaxation processes take place in which electronic and
nuclear motion are intimately coupled. These are best described by
the time-dependent molecular Schrödinger equation, but its
solution poses fundamental practical challenges to contemporary theoretical
chemistry. Two widely used and complementary approaches to this problem
are multiconfigurational time-dependent Hartree (MCTDH) and trajectory
surface hopping (SH). MCTDH is an accurate fully quantum-mechanical
technique but often is feasible only in reduced dimensionality, in
combination with approximate vibronic coupling (VC) Hamiltonians,
or both (i.e., reduced-dimensional VC potentials). In contrast, SH
is a quantum–classical technique that neglects most nuclear
quantum effects but allows nuclear dynamics in full dimensionality
by calculating potential energy surfaces on the fly. If nuclear quantum
effects do not play a central role and a linear VC (LVC) Hamiltonian
is appropriate—e.g., for stiff molecules that generally keep
their conformation in the excited state—then it seems advantageous
to combine the efficient LVC and SH techniques. In this Account, we
describe how surface hopping based on an LVC Hamiltonian (SH/LVC)—as
recently implemented in the SHARC surface hopping package—can
provide an economical and automated approach to simulate non-adiabatic
dynamics. First, we illustrate the potential of SH/LVC in a number
of showcases, including intersystem crossing in SO2, intra-Rydberg
dynamics in acetone, and several photophysical studies on large transition-metal
complexes, which would be much more demanding or impossible to perform
with other methods. While all of the applications provide very useful
insights into light-induced phenomena, they also hint at difficulties
faced by the SH/LVC methodology that need to be addressed in the future.
Second, we contend that the SH/LVC approach can be useful to benchmark
SH itself. By the use of the same (LVC) potentials as MCTDH calculations
have employed for decades and by relying on the efficiency of SH/LVC,
it is possible to directly compare multiple SH test calculations with
a MCTDH reference and ponder the accuracy of various correction algorithms
behind the SH methodology, such as decoherence corrections or momentum
rescaling schemes. Third, we demonstrate how the efficiency of SH/LVC
can also be exploited to identify essential nuclear and electronic
degrees of freedom to be employed in more accurate MCTDH calculations.
Lastly, we show that SH/LVC is able to advance the development of
SH protocols that can describe nuclear dynamics including explicit
laser fields—a very challenging endeavor for trajectory-based
schemes. To end, this Account compiles the typical costs of contemporary
SH simulations, evidencing the great advantages of using parametrized
potentials. The LVC model is a sleeping beauty that, kissed by SH,
is fueling the field of excited-state molecular dynamics. We hope
that this Account will stimulate future research in this direction,
leveraging the advantages of the SH/VC schemes to larger extents and
extending their applicability to uncharted territories.
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Affiliation(s)
- J. Patrick Zobel
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währingerstr. 19, 1090 Vienna, Austria
| | - Moritz Heindl
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währingerstr. 19, 1090 Vienna, Austria
| | - Felix Plasser
- Department of Chemistry, Loughborough University, Loughborough LE11 3TU, United Kingdom
| | - Sebastian Mai
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währingerstr. 19, 1090 Vienna, Austria
| | - Leticia González
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währingerstr. 19, 1090 Vienna, Austria
- Vienna Research Platform on Accelerating Photoreaction Discovery, University of Vienna, Währingerstr. 19, 1090 Vienna, Austria
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8
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Green JA, Yaghoubi Jouybari M, Asha H, Santoro F, Improta R. Fragment Diabatization Linear Vibronic Coupling Model for Quantum Dynamics of Multichromophoric Systems: Population of the Charge-Transfer State in the Photoexcited Guanine-Cytosine Pair. J Chem Theory Comput 2021; 17:4660-4674. [PMID: 34270258 DOI: 10.1021/acs.jctc.1c00416] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We introduce a method (FrD-LVC) based on a fragment diabatization (FrD) for the parametrization of a linear vibronic coupling (LVC) model suitable for studying the photophysics of multichromophore systems. In combination with effective quantum dynamics (QD) propagations with multilayer multiconfigurational time-dependent Hartree (ML-MCTDH), the FrD-LVC approach gives access to the study of the competition between intrachromophore decays, like those at conical intersections, and interchromophore processes, like exciton localization/delocalization and the involvement of charge-transfer (CT) states. We used FrD-LVC parametrized with time-dependent density functional theory (TD-DFT) calculations, adopting either CAM-B3LYP or ωB97X-D functionals, to study the ultrafast photoexcited QD of a guanine-cytosine (GC) hydrogen-bonded pair, within a Watson-Crick arrangement, considering up to 12 coupled diabatic electronic states and the effect of all of the 99 vibrational coordinates. The bright excited states localized on C and, especially, on G are predicted to be strongly coupled to the G → C CT state, which is efficiently and quickly populated after an excitation to any of the four lowest energy bright local excited states. Our QD simulations show that more than 80% of the excited population on G and ∼50% of that on C decay to this CT state in less than 50 fs. We investigate the role of vibronic effects in the population of the CT state and show that it depends mainly on its large reorganization energy so that it can occur even when it is significantly less stable than the bright states in the Franck-Condon region. At the same time, we document that the formation of the GC pair almost suppresses the involvement of dark nπ* excited states in the photoactivated dynamics.
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Affiliation(s)
- James A Green
- Istituto di Biostrutture e Bioimmagini (IBB-CNR), Consiglio Nazionale delle Ricerche, via Mezzocannone 16, I-80136 Napoli, Italy
| | - Martha Yaghoubi Jouybari
- Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR), Consiglio Nazionale delle Ricerche, SS di Pisa, Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa, Italy
| | - Haritha Asha
- Istituto di Biostrutture e Bioimmagini (IBB-CNR), Consiglio Nazionale delle Ricerche, via Mezzocannone 16, I-80136 Napoli, Italy
| | - Fabrizio Santoro
- Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR), Consiglio Nazionale delle Ricerche, SS di Pisa, Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa, Italy
| | - Roberto Improta
- Istituto di Biostrutture e Bioimmagini (IBB-CNR), Consiglio Nazionale delle Ricerche, via Mezzocannone 16, I-80136 Napoli, Italy
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9
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Green JA, Jouybari MY, Aranda D, Improta R, Santoro F. Nonadiabatic Absorption Spectra and Ultrafast Dynamics of DNA and RNA Photoexcited Nucleobases. Molecules 2021; 26:1743. [PMID: 33804640 PMCID: PMC8003674 DOI: 10.3390/molecules26061743] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/12/2021] [Accepted: 03/14/2021] [Indexed: 11/16/2022] Open
Abstract
We have recently proposed a protocol for Quantum Dynamics (QD) calculations, which is based on a parameterisation of Linear Vibronic Coupling (LVC) Hamiltonians with Time Dependent (TD) Density Functional Theory (TD-DFT), and exploits the latest developments in multiconfigurational TD-Hartree methods for an effective wave packet propagation. In this contribution we explore the potentialities of this approach to compute nonadiabatic vibronic spectra and ultrafast dynamics, by applying it to the five nucleobases present in DNA and RNA. For all of them we computed the absorption spectra and the dynamics of ultrafast internal conversion (100 fs timescale), fully coupling the first 2-3 bright states and all the close by dark states, for a total of 6-9 states, and including all the normal coordinates. We adopted two different functionals, CAM-B3LYP and PBE0, and tested the effect of the basis set. Computed spectra are in good agreement with the available experimental data, remarkably improving over pure electronic computations, but also with respect to vibronic spectra obtained neglecting inter-state couplings. Our QD simulations indicate an effective population transfer from the lowest energy bright excited states to the close-lying dark excited states for uracil, thymine and adenine. Dynamics from higher-energy states show an ultrafast depopulation toward the more stable ones. The proposed protocol is sufficiently general and automatic to promise to become useful for widespread applications.
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Affiliation(s)
- James A. Green
- CNR—Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini (IBB-CNR), Via Mezzocannone 16, I-80136 Napoli, Italy;
| | - Martha Yaghoubi Jouybari
- CNR—Consiglio Nazionale Delle Ricerche, Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR), SS di Pisa, Area Della Ricerca, Via G. Moruzzi 1, I-56124 Pisa, Italy; (M.Y.J.); (D.A.)
| | - Daniel Aranda
- CNR—Consiglio Nazionale Delle Ricerche, Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR), SS di Pisa, Area Della Ricerca, Via G. Moruzzi 1, I-56124 Pisa, Italy; (M.Y.J.); (D.A.)
| | - Roberto Improta
- CNR—Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini (IBB-CNR), Via Mezzocannone 16, I-80136 Napoli, Italy;
| | - Fabrizio Santoro
- CNR—Consiglio Nazionale Delle Ricerche, Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR), SS di Pisa, Area Della Ricerca, Via G. Moruzzi 1, I-56124 Pisa, Italy; (M.Y.J.); (D.A.)
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10
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Aleotti F, Aranda D, Yaghoubi Jouybari M, Garavelli M, Nenov A, Santoro F. Parameterization of a linear vibronic coupling model with multiconfigurational electronic structure methods to study the quantum dynamics of photoexcited pyrene. J Chem Phys 2021; 154:104106. [PMID: 33722019 DOI: 10.1063/5.0044693] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
With this work, we present a protocol for the parameterization of a Linear Vibronic Coupling (LVC) Hamiltonian for quantum dynamics using highly accurate multiconfigurational electronic structure methods such as RASPT2/RASSCF, combined with a maximum-overlap diabatization technique. Our approach is fully portable and can be applied to many medium-size rigid molecules whose excited state dynamics requires a quantum description. We present our model and discuss the details of the electronic structure calculations needed for the parameterization, analyzing critical situations that could arise in the case of strongly interacting excited states. The protocol was applied to the simulation of the excited state dynamics of the pyrene molecule, starting from either the first or the second bright state (S2 or S5). The LVC model was benchmarked against state-of-the-art quantum mechanical calculations with optimizations and energy scans and turned out to be very accurate. The dynamics simulations, performed including all active normal coordinates with the multilayer multiconfigurational time-dependent Hartree method, show good agreement with the available experimental data, endorsing prediction of the excited state mechanism, especially for S5, whose ultrafast deactivation mechanism was not yet clearly understood.
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Affiliation(s)
- Flavia Aleotti
- Dipartimento di Chimica Industriale "Toso Montanari," Università di Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy
| | - Daniel Aranda
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area della Ricerca del CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Martha Yaghoubi Jouybari
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area della Ricerca del CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Marco Garavelli
- Dipartimento di Chimica Industriale "Toso Montanari," Università di Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy
| | - Artur Nenov
- Dipartimento di Chimica Industriale "Toso Montanari," Università di Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy
| | - Fabrizio Santoro
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area della Ricerca del CNR, Via Moruzzi 1, I-56124 Pisa, Italy
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