A theory of vibrational structure in the X-ray spectra of molecules

Gel’mukhanov, Faris; Mazalov, L. N.; Kondratenko, A. V.

doi:10.1016/0009-2614(77)85180-4

Cited by 191 publications

(67 citation statements)

References 8 publications

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“…This differs from previous analyses 11 of subthreshold excited spectra which are based on momentum conservation for the overall scattering process: 4,6 Qϭk e Ϫk h ϩG, ͑8͒…”

Section: Resultscontrasting

confidence: 44%

“…In materials with weak electron correlations such as in many semiconductors and insulators, experimental data are often well interpreted using electronic states based on density-functional theory. For these kinds of broadband materials, a RIXS theory including resonance phenomena 4 and crystal momentum 5,6 has been established. The aspect of the one-step scattering treatment is that the conservation of momentum is important for the overall process.…”

Section: Introductionmentioning

confidence: 99%

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X-ray fluorescence spectra of metals excited below threshold

et al. 2003

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X-ray scattering spectra of Cu and Ni metals have been measured using monochromatic synchrotron radiation tuned from far above to more than 10 eV below threshold. Energy conservation in the scattering process is found to be sufficient to explain the modulation of the spectral shape, neglecting momentum conservation and channel interference. At excitation energies close to and above threshold, the emission spectra map the occupied local partial density of states. For the subthreshold excitations, the high-energy flank of the inelastic scattering exhibits a Raman-type linear dispersion, and an asymmetric low-energy tail develops. For excitation far below threshold the emission spectra are proportional to a convolution of the occupied and unoccupied local partial densities of states.

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“…This differs from previous analyses 11 of subthreshold excited spectra which are based on momentum conservation for the overall scattering process: 4,6 Qϭk e Ϫk h ϩG, ͑8͒…”

Section: Resultscontrasting

confidence: 44%

Section: Introductionmentioning

confidence: 99%

X-ray fluorescence spectra of metals excited below threshold

et al. 2003

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“…The minor differences could originate in differences in electronic structure between the gas-phase, as we consider, and the condensed-phase material probed in experiment. Additionally, we presently neglect vibronic coupling in the excited-state [67][68][69] which can be particularly important in molecules with light elements [70,71] …”

Section: Example Spectramentioning

confidence: 99%

Efficient implementation of core-excitation Bethe–Salpeter equation calculations

Gilmore

Vinson

Shirley

et al. 2015

Computer Physics Communications

163

177

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We present an efficient implementation of the Bethe-Salpeter equation (BSE) method for obtaining core-level spectra including x-ray absorption (XAS), x-ray emission (XES), and both resonant and non-resonant inelastic x-ray scattering spectra (N/RIXS). Calculations are based on density functional theory (DFT) electronic structures generated either by abinit or Quantumespresso, both plane-wave basis, pseudopotential codes. This electronic structure is improved through the inclusion of a GW self energy. The projector augmented wave technique is used to evaluate transition matrix elements between core-level and band states. Final two-particle scattering states are obtained with the NIST core-level BSE solver (NBSE). We have previously reported this implementation, which we refer to as ocean (Obtaining Core Excitations from Ab initio electronic structure and NBSE) [Phys. Rev. B 83, 115106 (2011)]. Here, we present additional efficiencies that enable us to evaluate spectra for systems ten times larger than previously possible; containing up to a few thousand electrons. These improvements include the implementation of optimal basis functions that reduce the cost of the initial DFT calculations, more complete parallelization of the screening calculation and of the action of the BSE Hamiltonian, and various memory reductions. Scaling is demonstrated on supercells of SrTiO 3 and example spectra for the organic light emitting molecule Tris-(8-hydroxyquinoline)aluminum (Alq 3 ) are presented. The ability to perform large-scale spectral calculations is particularly advantageous for investigating dilute or non-periodic systems such as doped materials, amorphous systems, or complex nano-structures.

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“…As has been demonstrated in these studies, lifetime vibrational interference (LVI, [20]) is the dominant effect in the solid-angle-averaged or magic-angle-recorded deexcitation spectra of the resonances. Interference between excitation-deexcitation pathways via different intermediate electronic resonances, known as electronic state interference (ESI, [21]), shows up in the decay spectra only, if the angular averaging is reduced [15,19].…”

Section: Introductionmentioning

confidence: 53%