TD-DFT simulations of K-edge resonant inelastic X-ray scattering within the restricted subspace approximation

Cruz, Vinícius Vaz da; Eckert, Sebastian; Föhlisch, Alexander

doi:10.1039/d0cp04726k

Cited by 24 publications

(37 citation statements)

References 77 publications

(137 reference statements)

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“…The most prominent signatures at resonant excitation are the two intense and narrow emission lines at approximately 5 and 6 eV energy loss. To assess the origin of the different emission features, we focus on the electronic structure and RSA-TD-DFT 27 spectrum simulations (based on the Kramers–Heisenberg formalism) of the fully symmetric isolated pyrimidine molecule in Figure 1 b. Thereby, we relate the emission lines to decay from the symmetric and antisymmetric combination of occupied lone-pair orbitals, the 11a 1 and 7b 2 orbitals (see Figure 1 b), these orbitals are split by ∼1 eV due to overlap with the ring σ orbitals.…”

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confidence: 99%

Breaking the Symmetry of Pyrimidine: Solvent Effects and Core-Excited State Dynamics

Eckert

Cruz

Ochmann

et al. 2021

J. Phys. Chem. Lett.

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Symmetry and its breaking crucially define the chemical properties of molecules and their functionality. Resonant inelastic X-ray scattering is a local electronic structure probe reporting on molecular symmetry and its dynamical breaking within the femtosecond scattering duration. Here, we study pyrimidine, a system from the C 2 v point group, in an aqueous solution environment, using scattering though its 2a 2 resonance. Despite the absence of clean parity selection rules for decay transitions from in-plane orbitals, scattering channels including decay from the 7b 2 and 11a 1 orbitals with nitrogen lone pair character are a direct probe for molecular symmetry. Computed spectra of explicitly solvated molecules sampled from a molecular dynamics simulation are combined with the results of a quantum dynamical description of the X-ray scattering process. We observe dominant signatures of core-excited Jahn–Teller induced symmetry breaking for resonant excitation. Solvent contributions are separable by shortening of the effective scattering duration through excitation energy detuning.

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confidence: 99%

Breaking the Symmetry of Pyrimidine: Solvent Effects and Core-Excited State Dynamics

Eckert

Cruz

Ochmann

et al. 2021

J. Phys. Chem. Lett.

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“…We found that the energy of the 3sσ peak moved to slightly higher energy, while the other peak energies were unaffected. We attribute the remaining residuals in the π * resonance to a combination of unresolved vibrational structure [51,52] [45] for the two resolved symmetry directions 0 • (solid) and 90 • (dashed). Solid gray and dashed-dotted gray line indicated their data, for 0 • and 90 • , respectively.…”

Section: Co 2 Oxygen K-edgementioning

confidence: 99%

“…However, the lowest energy line has significant residuals. These residuals may originate from a combination of unresolved vibrational structure [51,52] and a possibly non-ideal instrument lineshape.…”

Section: Sf 6 Fluorine K-edgementioning

confidence: 99%

“…We found that the energy of the peak moved to slightly higher energy, while the other peak energies were unaffected. We attribute the remaining residuals in the resonance to a combination of unresolved vibrational structure [ 51 , 52 ] and a possible non-ideal instrument lineshape. The dominant uncertainty in the transition energy determination is drift in the monochromator energy scale.…”

Section: Energy Calibration Of Andmentioning

confidence: 99%

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A new benchmark of soft X-ray transition energies of $$\mathrm {Ne}$$, $$\mathrm {CO}_2$$, and $$\mathrm {SF}_6$$: paving a pathway towards ppm accuracy

et al. 2022

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A key requirement for the correct interpretation of high-resolution X-ray spectra is that transition energies are known with high accuracy and precision. We investigate the K-shell features of $$\mathrm {Ne}$$ Ne , $$\mathrm {CO}_2$$ CO 2 , and $$\mathrm {SF}_6$$ SF 6 gases, by measuring their photo ion-yield spectra at the BESSY II synchrotron facility simultaneously with the 1s–np fluorescence emission of He-like ions produced in the Polar-X EBIT. Accurate ab initio calculations of transitions in these ions provide the basis of the calibration. While the $$\mathrm {CO}_2$$ CO 2 result agrees well with previous measurements, the $$\mathrm {SF}_6$$ SF 6 spectrum appears shifted by $$\sim $$ ∼ 0.5 eV, about twice the uncertainty of the earlier results. Our result for $$\mathrm {Ne}$$ Ne shows a large departure from earlier results, but may suffer from larger systematic effects than our other measurements. The molecular spectra agree well with our results of time-dependent density functional theory. We find that the statistical uncertainty allows calibrations in the desired range of 1–10 meV, however, systematic contributions still limit the uncertainty to $${\sim }$$ ∼ 40–100 meV, mainly due to the temporal stability of the monochromator energy scale. Combining our absolute calibration technique with a relative energy calibration technique such as photoelectron energy spectroscopy will be necessary to realize its full potential of achieving uncertainties as low as 1–10 meV. Graphical abstract

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“…Thus, in the context of core-excited state dynamics, the exploration of core-excited state potential energy surfaces at the CVS-ADC level of theory becomes a realistic and interesting application. This aspect has motivated us to derive and implement molecular gradients up to the CVS-ADC(2)-x level of theory, opening the door for performing core-excited state structure optimizations (as illustrated here), including vibrational effects in X-ray spectra calculations, 18,19 and simulating core-excited state dynamics by using, for example, the surface hopping technique [20][21][22] (potentially on a highly reliable PES with interpolation). [23][24][25] Our derivation is based on the Lagrangian method which is well-established for analytical gradients, but has not yet been applied to the CVS approximation.…”

Section: Introductionmentioning

confidence: 99%

Analytical Gradients for Core-Excited States in the Algebraic Diagrammatic Construction (ADC) Framework

Brumboiu

Rehn²,

Dreuw³

et al. 2021

Preprint

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Here we present a derivation of the analytical expressions required to determine nuclear gradients for core-excited states at the core-valence separated algebraic diagrammatic construction (CVS-ADC) theory level. Analytical gradients up to and including the extended CVS-ADC(2)-x order have been derived and implemented into a Python module, adc_gradient. The gradients were used to determine core-excited state optimized geometries and relaxed potential energy surfaces for the water, formic acid, and benzne molecules. <br>

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TD-DFT simulations of K-edge resonant inelastic X-ray scattering within the restricted subspace approximation

Abstract: A scheme for simulations of resonant inelastic X-ray scattering (RIXS) cross-sections within time-dependent density functional theory (TD-DFT) applying the restricted subspace approximation (RSA) is presented. Therein both occupied core and...

Cited by 24 publications

References 77 publications

Breaking the Symmetry of Pyrimidine: Solvent Effects and Core-Excited State Dynamics

Breaking the Symmetry of Pyrimidine: Solvent Effects and Core-Excited State Dynamics

A new benchmark of soft X-ray transition energies of $$\mathrm {Ne}$$, $$\mathrm {CO}_2$$, and $$\mathrm {SF}_6$$: paving a pathway towards ppm accuracy

Analytical Gradients for Core-Excited States in the Algebraic Diagrammatic Construction (ADC) Framework

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