Time-dependent theory of Raman scattering

Lee, Soo‐Y.; Heller, Eric J.

doi:10.1063/1.438316

Cited by 761 publications

(580 citation statements)

References 17 publications

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“…In the time domain arguably the best approach is to perform wavepacket quantum dynamics numerically exactly. 9,[11][12][13][14][15] However, it usually requires an expensive pre-computation of many-dimensional potential energy surfaces (PES) and is limited to small systems or is based on a reduction of dimensionality. Many attempts to bridge the gap between the two extrema, which are not possible to review in detail here, were made, see Refs.…”

Section: Introductionmentioning

confidence: 99%

Quasi-classical approaches to vibronic spectra revisited

Karsten

Ivanov

Bokarev

et al. 2018

The Journal of Chemical Physics

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The framework to approach quasi-classical dynamics in the electronic ground state is well established and is based on the Kubo-transformed time correlation function (TCF), being the most classical-like quantum TCF. Here we discuss whether the choice of the Kubo-transformed TCF as a starting point for simulating vibronic spectra is as unambiguous as it is for vibrational ones. A generalized quantum TCF is proposed that contains many of the well-established TCFs as particular cases. It provides a framework to develop numerical protocols for simulating vibronic spectra via quasi-classical trajectory-based methods that allow for dynamics on many potential energy surfaces and nuclear quantum effects. The performance of the methods based on the well-known TCFs is investigated on 1D anharmonic model systems at finite temperatures. The flexibility inherent to the formulation of the generalized TCF provides a route to construct new TCFs that may lead to better numerical protocols as is shown on the same models.

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Section: Introductionmentioning

confidence: 99%

Quasi-classical approaches to vibronic spectra revisited

Karsten

Ivanov

Bokarev

et al. 2018

The Journal of Chemical Physics

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“…These optimal linear combinations being field specific, a comprehensive analysis will require the optimizations to be carried out and the structural features of the optimal initial state to be analyzed for a sufficiently large number of field parameters. Instead, the time dependent wave packet ͑TDWP͒ method pioneered by Heller [22][23][24] permits the evaluation of branching ratios for a large number of frequencies from a single calculation, 25 where, in our case, the initial wave packet to be promoted to the excited electronic states is the optimal superposition of the field free eigenstates for the given photolysis pulse and chosen photodissociation objective.…”

Section: Introductionmentioning

confidence: 99%

Photodynamic control using field optimized initial state: A mechanistic investigation of selective control with application to IBr and HI photodissociation

Vandana

Mishra

1999

The Journal of Chemical Physics

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The probability density profiles from the optimal superpositions of the field free vibrational eigenstates which maximize flux out of the desired photodissociation channels are examined for IBr and HI molecules. Analysis of the structure in these optimal superposition states obtained by applying the Rayleigh-Ritz variational procedure to the time integrated flux operator shows that the transfer of probability density to appropriate areas of the Franck-Condon region on the excited surfaces is responsible for selective flux maximization out of different channels. Localizing the wave packet on the more repulsive part of the higher curve facilitates fast diabatic exit out of the upper channel and transition to the less repulsive part promotes slow adiabatic exit out of the lower channel. This mechanism is further probed by utilizing time dependent wave packet dynamics to obtain absorption spectra and branching ratios using full Fourier transform of the autocorrelation functions for these field optimized initial states. The results corroborate the central role of altered spatial profile of the initial state in selective control of photodissociation.

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“…We have adopted a method that uses an analytic representation of the WP based on Heller's semiclassical approach and has proven to provide an excellent agreement with the numerical solution of the time-dependent Schrödinger equation [38,45,46]. Fig.…”

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confidence: 99%

Potential Energy Surface Reconstruction and Lifetime Determination of Molecular Double-Core-Hole States in the Hard X-Ray Regime

et al. 2017

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A combination of resonant inelastic x-ray scattering and resonant Auger spectroscopy provides complementary information on the dynamic response of resonantly excited molecules. This is exemplified for CH3I, for which we reconstruct the potential energy surface of the dissociative I 3d −2 double-core-hole state and determine its lifetime. The proposed method holds a strong potential for monitoring the hard x-ray induced electron and nuclear dynamic response of core-excited molecules containing heavy elements, where ab initio calculations of potential energy surfaces and lifetimes remain challenging.Hard x-ray radiation, with photon energy above 1 keV, can excite deep core shells of heavy atoms (Cl 1s, S 1s, I 2p etc) and may cause breakage of the chemical bonds and drastic changes to the electronic structure. The interplay between the induced nuclear and electron dynamics determines the response of a core-excited molecule. In the case of resonant excitation to a dissociative molecular state, the time evolution of the relaxation process is determined by the potential energy surface (PES) and the lifetime of the excited state. The so called "core-hole clock" spectroscopy (CHCS) allows probing ultrafast dynamics, occurring in a resonantly core-excited molecule within the core-hole lifetime, through control over the photon energy [1][2][3][4].Resonant inelastic x-ray scattering (RIXS) and resonant Auger electron spectroscopy (RAS) are the two CHCS techniques relevant, respectively, to the measurements of x-ray photons or Auger electrons emitted in the course of relaxation of core-excited molecular states. As the probability of radiative relaxation of core-excited atoms increases with atomic number, both RIXS and RAS become equally relevant in the hard x-ray regime [5][6][7][8][9][10][11][12][13][14]. However, the major difference between these techniques appears in the electronic final states reached upon relaxation. In the case of RIXS, the molecule remains neutral with an electron in the excited orbital and a single hole, whereas in the case of resonant spectator Auger decay, the molecule becomes singly charged with an electron in the excited orbital and a double hole.Spectroscopy of double core-hole (DCH) states, created either with intense XFEL radiation through multiphoton absorption [15][16][17] or with high-energy photons provided by synchrotron radiation [18][19][20][21][22][23], has been a hot topic in the recent years. Understanding the nuclear dynamics of DCH states in molecules, formed in the course of cascade relaxations, is of particular interest in relation to the radiation-induced damage in organic tissue and coherent diffraction imaging [24,25].In this Letter, we demonstrate an original method to extract information on the electron and nuclear dynamic response of molecules in DCH states, created with hard x-ray radiation. In contrast to soft x-ray region, where nuclear dynamics occurs in a core-excited state, a short lifetime of a core-excited state in the hard x-ray regime allows a simple and, hence...

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Time-dependent theory of Raman scattering

Cited by 761 publications

References 17 publications

Quasi-classical approaches to vibronic spectra revisited

Quasi-classical approaches to vibronic spectra revisited

Photodynamic control using field optimized initial state: A mechanistic investigation of selective control with application to IBr and HI photodissociation

Potential Energy Surface Reconstruction and Lifetime Determination of Molecular Double-Core-Hole States in the Hard X-Ray Regime

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