Many-Body Effects in the X-ray Absorption Spectra of Liquid Water

Abstract

X-ray absorption spectroscopy (XAS) is a powerful experimental technique to probe the local order in materials with core electron excitations. Experimental interpretation requires supporting theoretical calculations. For water, these calculations are very demanding and, to date, could only be done with major approximations that limited the accuracy of the calculated spectra. This prompted an intense debate on whether a substantial revision of the standard picture of tetrahedrally bonded water was necessary to improve the agreement of theory and experiment. Here, we report a new first-principles calculation of the XAS of water that avoids the approximations of prior work thanks to recent advances in electron excitation theory. The calculated XAS spectra, and their variation with changes of temperature and/or with isotope substitution, are in excellent quantitative agreement with experiments. The approach requires accurate quasi-particle wavefunctions beyond density functional theory approximations, accounts for the dynamics of quasi-particles and includes dynamic screening as well as renormalization effects due to the continuum of valence-level excitations. The three features observed in the experimental spectra are unambiguously attributed to excitonic effects. The pre-edge feature is associated to a bound intramolecular exciton, the main-edge feature is associated to an exciton localized within the coordination shell of the excited molecule, while the post-edge one is delocalized over more distant neighbors, as expected for a resonant state. The three features probe the local order at short, intermediate, and longer range relative to the excited molecule. The calculated spectra are fully consistent with a standard tetrahedral picture of water.

arXiv comment11 pages, 3 figures

References in corpus (23)

• Optimized norm-conserving Vanderbilt pseudopotentials
• The GW method
• BerkeleyGW: A Massively Parallel Computer Package for the Calculation of the Quasiparticle and Optical Properties of Materials and Nanostructures
• Resolution-of-identity approach to Hartree-Fock, hybrid density functionals, RPA, MP2, and \textit{GW} with numeric atom-centered orbital basis functions
• Ab initio theory and modeling of water
• The Individual and Collective Effects of Exact Exchange and Dispersion Interactions on the Ab Initio Structure of Liquid Water
• Bethe-Salpeter Equation Calculations of Core Excitation Spectra
• Nuclear quantum effects in solids using a colored-noise thermostat
• Machine-Learning X-ray Absorption Spectra to Quantitative Accuracy
• The bandstructure of gold from many-body perturbation theory
• Effects of polarization on the band-structure of delafossite transparent conductive oxides
• X-ray absorption signatures of the molecular environment in water and ice
• Electron-hole theory of the effect of quantum nuclei on the x-ray absorption spectra of liquid water
• Many-body Green's function GW and Bethe-Salpeter study of the optical excitations in a paradigmatic model dipeptide
• Addressing electron-hole correlation in core excitations of solids: An all-electron many-body approach from first principles
• Role of quantum nuclei and local fields in the x-ray absorption spectra of water and ice
• Theoretical optical and x-ray spectra of liquid and solid H_2O
• First-Principles Description of Charge Transfer in Donor-Acceptor Compounds from Self-Consistent Many-Body Perturbation Theory
• Many-Body Effects in the X-ray Absorption Spectra of Liquid Water
• Solving the Bethe-Salpeter Equation on a Subspace: Approximations and Consequences for Low-dimensional Materials
• Excitation Pathways in Resonant Inelastic X-Ray Scattering of Solids
• X-ray absorption of liquid water by advanced ab initio methods
• Isotope effects in x-ray absorption spectra of liquid water

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