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Effects of Li Confined Motion on NMR Quadrupolar Interactions: A Combined 7 Li NMR and DFT‐MD Study of LiR 2 (PO 4 ) 3 (R=Ti or Zr) Phases
Author(s) -
DiezGómez Virginia,
Andres Pedro L.,
Sanz Jesús
Publication year - 2020
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201902991
Subject(s) - chemistry , triclinic crystal system , ion , molecular dynamics , ab initio quantum chemistry methods , anisotropy , ab initio , crystallography , molecular physics , computational chemistry , crystal structure , molecule , physics , organic chemistry , quantum mechanics
Ab initio molecular dynamics (MD) simulations and NMR GIPAW (gauge including projector augmented wave) calculations have been used to analyze the coordination and mobility of Li ions in LiTi 2 (PO 4 ) 3 (rhombohedral), LiZr 2 (PO 4 ) 3 (triclinic), and LiZr 2 (PO 4 ) 3 (rhombohedral) phases. Significant discrepancies are observed between static calculations of 7 Li quadrupolar parameters and experimental values. The dynamical origin of this disagreement is demonstrated by incorporating in the calculations thermal vibrations and local motion of atoms with MD simulations. For LiTi 2 (PO 4 ) 3 , the quadrupolar constant associated with Li ions grows with temperature because the local symmetry of the system decreases, whereas for the Zr phases, the quadrupolar constant decreases because thermal vibrations reduce the anisotropy of the interaction. Finally, for both Zr phases, MD yields Li distributions that compare well with disorder reported from diffraction studies.