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Title: Finite temperature effects on the X-ray absorption spectra of lithium compounds: First-principles interpretation of X-ray Raman measurements

We elucidate the role of room-temperature-induced instantaneous structural distortions in the Li K-edge X-ray absorption spectra (XAS) of crystalline LiF, Li{sub 2}SO{sub 4}, Li{sub 2}O, Li{sub 3}N, and Li{sub 2}CO{sub 3} using high resolution X-ray Raman spectroscopy (XRS) measurements and first-principles density functional theory calculations within the eXcited electron and Core Hole approach. Based on thermodynamic sampling via ab initio molecular dynamics simulations, we find calculated XAS in much better agreement with experiment than those computed using the rigid crystal structure alone. We show that local instantaneous distortion of the atomic lattice perturbs the symmetry of the Li 1s core-excited-state electronic structure, broadening spectral line-shapes and, in some cases, producing additional spectral features. The excellent agreement with high-resolution XRS measurements validates the accuracy of our first-principles approach to simulating XAS, and provides both accurate benchmarks for model compounds and a predictive theoretical capability for identification and characterization of multi-component systems, such as lithium-ion batteries, under working conditions.
Authors:
;  [1] ; ; ;  [2] ; ; ;  [3] ; ;  [4] ;  [2] ;  [5]
  1. The Molecular Foundry, Materials Science Division, Lawrence Berkeley National Laboratory (LBNL), Berkeley, California 94720 (United States)
  2. Environmental Energy Technologies Division, LBNL, Berkeley, California 94720 (United States)
  3. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford, California 94720 (United States)
  4. University of Saskatchewan, Department of Physics and Engineering Physics, Saskatoon, Saskatchewan S7N 5E2 (Canada)
  5. (United States)
Publication Date:
OSTI Identifier:
22255278
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; ACCURACY; CRYSTAL STRUCTURE; DENSITY FUNCTIONAL METHOD; ELECTRIC BATTERIES; ELECTRONIC STRUCTURE; EXCITED STATES; LITHIUM CARBONATES; LITHIUM FLUORIDES; LITHIUM IONS; LITHIUM NITRIDES; LITHIUM OXIDES; LITHIUM SULFATES; MOLECULAR DYNAMICS METHOD; RAMAN SPECTROSCOPY; SIMULATION; TEMPERATURE DEPENDENCE; X RADIATION; X-RAY SPECTRA; X-RAY SPECTROSCOPY