title: Finite temperature effects on the X-ray absorption spectra of lithium compounds: first-principles interpretation of X-ray Raman measurements.
abstract: We elucidate the role of room-temperature-induced instantaneous structural distortions in the Li K-edge X-ray absorption spectra (XAS) of crystalline LiF, Li2SO4, Li2O, Li3N, and Li2CO3 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: The Molecular Foundry, Materials Science Division, Lawrence Berkeley National Laboratory (LBNL), Berkeley, California 94720, USA.
authors: Tod A
authors: TA
authors: Pascal
authors: Environmental Energy Technologies Division, LBNL, Berkeley, California 94720, USA.
authors: Ulrike
authors: U
authors: Boesenberg
authors: Environmental Energy Technologies Division, LBNL, Berkeley, California 94720, USA.
authors: Robert
authors: R
authors: Kostecki
authors: Environmental Energy Technologies Division, LBNL, Berkeley, California 94720, USA.
authors: Thomas J
authors: TJ
authors: Richardson
authors: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford, California 94720, USA.
authors: Tsu-Chien
authors: TC
authors: Weng
authors: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford, California 94720, USA.
authors: Dimosthenis
authors: D
authors: Sokaras
authors: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford, California 94720, USA.
authors: Dennis
authors: D
authors: Nordlund
authors: University of Saskatchewan, Department of Physics and Engineering Physics, Saskatoon, Saskatchewan S7N 5E2, Canada.
authors: Eamon
authors: E
authors: McDermott
authors: University of Saskatchewan, Department of Physics and Engineering Physics, Saskatoon, Saskatchewan S7N 5E2, Canada.
authors: Alexander
authors: A
authors: Moewes
authors: Environmental Energy Technologies Division, LBNL, Berkeley, California 94720, USA.
authors: Jordi
authors: J
authors: Cabana
authors: The Molecular Foundry, Materials Science Division, Lawrence Berkeley National Laboratory (LBNL), Berkeley, California 94720, USA.
authors: David
authors: D
authors: Prendergast