Semiclassical vibrational spectroscopy with Hessian databases

Conte, Riccardo; Gabas, F.; Botti, Giacomo; Zhuang, Yu; Ceotto, Michele

doi:10.1063/1.5109086

Cited by 28 publications

(52 citation statements)

References 86 publications

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“…This can become rather costly for accurate ab initio calculations of large molecules. 36,60,[69][70][71][72][73][74][75][76][77][78][79][80] For this reason, two of us have proposed the single-Hessian thawed Gaussian approximation, 39 where…”

Section: Evaluating Spectra Beyond Condon and Harmonic Approximationsmentioning

confidence: 99%

Semiclassical Approach to Photophysics Beyond Kasha’s Rule and Vibronic Spectroscopy Beyond the Condon Approximation. The Case of Azulene

Prlj

Begušić

Zhang

et al. 2020

J. Chem. Theory Comput.

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Azulene is a prototypical molecule with an anomalous fluorescence from the second excited electronic state, thus violating Kasha's rule, and with an emission spectrum that cannot be understood within the Condon approximation. To better understand photophysics and spectroscopy of azulene and other non-conventional molecules, we develop a systematic, general, and efficient computational approach combining semiclassical dynamics of nuclei with ab initio electronic structure. First, to analyze the nonadiabatic effects, we complement the standard population dynamics by a rigorous 1 arXiv:2001.08414v2 [physics.chem-ph] measure of adiabaticity, estimated with the multiple-surface dephasing representation.Second, we propose a new semiclassical method for simulating non-Condon spectra, which combines the extended thawed Gaussian approximation with the efficient single-Hessian approach. S 1 ← S 0 and S 2 ← S 0 absorption and S 2 → S 0 emission spectra of azulene, recorded in a new set of experiments, agree very well with our calculations. We find that accuracy of the evaluated spectra requires the treatment of anharmonicity, Herzberg-Teller, and mode-mixing effects.

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Section: Evaluating Spectra Beyond Condon and Harmonic Approximationsmentioning

confidence: 99%

Semiclassical Approach to Photophysics Beyond Kasha’s Rule and Vibronic Spectroscopy Beyond the Condon Approximation. The Case of Azulene

Prlj

Begušić

Zhang

et al. 2020

J. Chem. Theory Comput.

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show abstract

“…Within this formalism it was possible to reproduce vibrational spectra of small molecules by evolving roughly only one thousand classical trajectories per degree of freedom, [73][74][75][76][77][78] also demonstrating that it does not suffer from ZPE leakage, 79 and that the cost of evaluating the Hessian can be reduced by employing a database. 80 With a careful choice of initial conditions, it is even possible to employ a single classical trajectory per sought spectral peak, via the Multiple Coherent State (MC SCIVR) approach. [81][82][83][84][85][86][87][88][89][90] Impressive results have also been obtained with the Thawed Gaussian approach.…”

Section: A Semiclassical Cartesian Propagatormentioning

confidence: 99%

Reduced rovibrational coupling Cartesian dynamics for semiclassical calculations: Application to the spectrum of the Zundel cation

Bertaina

Liberto

Ceotto

2019

The Journal of Chemical Physics

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We study the vibrational spectrum of the protonated water dimer, by means of a divide-and-conquer semiclassical initial value representation of the quantum propagator, as a first step in the study of larger protonated water clusters. We use the potential energy surface from [Huang et al., J. Chem. Phys. 122, 044308 (2005)]. To tackle such an anharmonic and floppy molecule, we employ fully Cartesian dynamics and carefully reduce the coupling to global rotations in the definition of normal modes. We apply the time-averaging filter and obtain clean power spectra relative to suitable reference states, that highlight the spectral peaks corresponding to the fundamental excitations of the system. Our trajectory-based approach allows us for physical interpretation of the very challenging proton transfer modes. We find that it is important, for such a floppy molecule, to selectively avoid to initially excite lower energy modes, in order to obtain cleaner spectra. The estimated vibrational energies display a mean absolute error (MAE) of ∼ 29cm −1 with respect to available Multi-Configuration time-dependent Hartree calculations and MAE ∼ 14cm −1 when compared to the optically active experimental excitations of the Ne-tagged Zundel cation. The reasonable scaling in the number of trajectories for Monte Carlo convergence is promising for applications to higher dimensional protonated cluster systems.The Zundel cation is the most representative member of the family of protonated water clusters, towards which many computational efforts are being devoted, mainly motivated by a flourishing of experimental results, 11-16 and the request for higher accuracy. [17][18][19][20][21] In this respect, this molecule is a prototypical example that has been tackled by various approaches, given the great biological relevance of the charge transport mechanism in aqueous solutions. [22][23][24][25][26][27] On the experimental side, the vibrational spectrum of the Zundel cation has been investigated by infrared multiphoton photodissociation spectroscopy 28,29 and noble gases predissociation spectroscopy, in particular Argon and Neon. [30][31][32] The theoretical literature about the vibrational spectrum of the Zundel cation is quite vast, since its strong anharmonicity provides the ideal test-bed for theoretical methods. The PES computed at the level of coupled cluster theory and devised in Ref. 33, has been employed by a plethora of methods for vibrational calculations, such as vibrational configuration interaction (VCI), 34 diffusion Monte Carlo, 32,35 classical molecu-

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“…[33][34][35] Finally, recent advances in the field have permitted to determine vibrational eigenfunctions, [36,37] IR spectra, [38] decrease substantially the impact of deterministic chaos on SC simulations leading to more accurate and precise results, [39] and decrease the computational overhead related to Hessian calculations. [40][41][42][43] The last aspect points out why "on-the-fly" SCIVR calculations are so computationally demanding. The reason is that ab initio electronic calculations must be perfomed not only for energies and gradients, but also for the Hessian matrix of the potential.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of semiclassical vibrational spectroscopy to potential energy surface accuracy: A test on formaldehyde

Conte

Botti

Ceotto

2020

Vibrational Spectroscopy

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A set of permutationally invariant potential energy surfaces for the electronic ground state of formaldehyde is built at several levels of electronic theory and atomic orbital basis sets starting from a database of more than 34000 ab initio energies. Preliminarily, the reliability of the fitted surfaces is determined by comparing the calculated harmonic frequencies with the corresponding ab initio values. Then, semiclassical estimates of the quantum frequencies of vibration are presented, and their dependence on the employed level of theory, type of atomic orbital basis set, and complexity of the fit is investigated. Comparisons of semiclassical results to experimental data provide a further assessment of the quality of the analytical surfaces and show that anharmonic frequencies are influenced by the precision of the fit, while accurate frequency values are obtained also with density functional theory. Results and conclusions support the use of ab initio "on-the-fly" semiclassical dynamics as a means of spectroscopic investigation when high-level analytical potential energy surfaces are not available.

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Semiclassical vibrational spectroscopy with Hessian databases

Cited by 28 publications

References 86 publications

Semiclassical Approach to Photophysics Beyond Kasha’s Rule and Vibronic Spectroscopy Beyond the Condon Approximation. The Case of Azulene

Semiclassical Approach to Photophysics Beyond Kasha’s Rule and Vibronic Spectroscopy Beyond the Condon Approximation. The Case of Azulene

Reduced rovibrational coupling Cartesian dynamics for semiclassical calculations: Application to the spectrum of the Zundel cation

Sensitivity of semiclassical vibrational spectroscopy to potential energy surface accuracy: A test on formaldehyde

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