Regularized weighted sine least-squares spectral analysis for gas electron diffraction data

Tikhonov, Denis S.

doi:10.1063/5.0168417

Cited by 3 publications

(10 citation statements)

References 64 publications

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“…In particular, here, we used the regularized weighted LSSA (rwLSSA) introduced in Ref. [68] (see details in Appendix C). The rwLSSA spectrum of delay range of −0.7 ≤ t pp < 30 ps for a frequency range of 0 < ω ≤ 7 THz is shown in Figure 12.…”

Section: Treatment Of the Data With Coherent Oscillationsmentioning

confidence: 99%

“…The detailed derivation of the rwLSSA technique is provided in Ref. [68], focusing on the sine-FT. Here, we only outline the basic steps of the method for the general case of the FT.…”

Section: Supplementary Materialsmentioning

confidence: 99%

“…The uncertainties of the spectral amplitudes ς m are computed from the m-th diagonal elements Σ α,mm and (S † W S) mm of the matrices Σ α and (S † W S), respectively, as [68]:…”

Section: Supplementary Materialsmentioning

confidence: 99%

“…The regularization parameter was chosen automatically with an a priori regularization criterion from Ref. [68] as:…”

Section: Supplementary Materialsmentioning

confidence: 99%

“…Then, we perform an rwLSSA analysis [68] (see Appendix C) for the residuals of the fit that are also printed by the PP(MC) 3 Fitting. This analysis will allow us to check whether the signal contains any systematic oscillations.…”

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confidence: 99%

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Inverse Problems in Pump–Probe Spectroscopy

Tikhonov,

Garg,

Schnell

2024

Photochem

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Ultrafast pump–probe spectroscopic studies allow for deep insights into the mechanisms and timescales of photophysical and photochemical processes. Extracting valuable information from these studies, such as reactive intermediates’ lifetimes and coherent oscillation frequencies, is an example of the inverse problems of chemical kinetics. This article describes a consistent approach for solving this inverse problem that avoids the common obstacles of simple least-squares fitting that can lead to unreliable results. The presented approach is based on the regularized Markov Chain Monte-Carlo sampling for the strongly nonlinear parameters, allowing for a straightforward solution of the ill-posed nonlinear inverse problem. The software to implement the described fitting routine is introduced and the numerical examples of its application are given. We will also touch on critical experimental parameters, such as the temporal overlap of pulses and cross-correlation time and their connection to the minimal reachable time resolution.

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Section: Treatment Of the Data With Coherent Oscillationsmentioning

confidence: 99%

“…The detailed derivation of the rwLSSA technique is provided in Ref. [68], focusing on the sine-FT. Here, we only outline the basic steps of the method for the general case of the FT.…”

Section: Supplementary Materialsmentioning

confidence: 99%

“…The uncertainties of the spectral amplitudes ς m are computed from the m-th diagonal elements Σ α,mm and (S † W S) mm of the matrices Σ α and (S † W S), respectively, as [68]:…”

Section: Supplementary Materialsmentioning

confidence: 99%

“…The regularization parameter was chosen automatically with an a priori regularization criterion from Ref. [68] as:…”

Section: Supplementary Materialsmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Inverse Problems in Pump–Probe Spectroscopy

Tikhonov,

Garg,

Schnell

2024

Photochem

Self Cite

View full text Add to dashboard Cite

show abstract

Inverse Problems in Pump-Probe Spectroscopy

Tikhonov,

Garg,

Schnell

2024

Preprint

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Ultrafast pump-probe spectroscopic studies allow for deep insights into the mechanisms and timescales of photophysical and photochemical processes. Extracting valuable information from these studies, such as reactive intermediates' lifetimes and coherent oscillation frequencies, is an example of the inverse problems of chemical kinetics. This article describes a consistent approach for solving this inverse problem that avoids the common obstacles of simple least-squares fitting that can lead to unreliable results. The presented approach is based on the regularized Markov Chain Monte Carlo sampling for the strongly nonlinear parameters, allowing for a straightforward solution of the ill-posed nonlinear inverse problem. The software to implement the described fitting routine is introduced and the numerical examples of its application are given. We will also touch on critical experimental parameters, such as the temporal overlap of pulses and cross-correlation time and their connection to the minimal reachable time resolution.

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PyRAMD Scheme: A Protocol for Computing the Infrared Spectra of Polyatomic Molecules Using ab Initio Molecular Dynamics

Tikhonov

2024

Spectroscopy Journal

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Here, we present a general framework for computing the infrared anharmonic vibrational spectra of polyatomic molecules using Born–Oppenheimer molecular dynamics (BOMD) with PyRAMD software. To account for nuclear quantum effects, we suggest using a simplified Wigner sampling (SWS) approach simultaneously coupled with Andersen and Berendsen thermostats. We propose a new criterion for selecting the parameter of the SWS based on the molecules’ harmonic vibrational frequencies and usage of the large-time-step blue shift correction, allowing for a decrease in computational expenses. For the Fourier transform of the dipole moment autocorrelation function, we propose using the regularized least-squares analysis, which allows us to obtain higher-frequency resolution than with the direct application of fast Fourier transform. Finally, we suggest the usage of the pre-parameterized scaling factors for the IR spectra from BOMD, also providing the scaling factors for the spectra at the BLYP-D3(BJ)/6-31G, PBE-D3(BJ)/6-31G, and PBEh-3c levels of theory.

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Regularized weighted sine least-squares spectral analysis for gas electron diffraction data

Cited by 3 publications

References 64 publications

Inverse Problems in Pump–Probe Spectroscopy

Inverse Problems in Pump–Probe Spectroscopy

Inverse Problems in Pump-Probe Spectroscopy

PyRAMD Scheme: A Protocol for Computing the Infrared Spectra of Polyatomic Molecules Using ab Initio Molecular Dynamics

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