First-principles calculation of the 17O NMR parameters in Ca oxide and Ca aluminosilicates: the partially covalent nature of the Ca-O bond, a challenge for density functional theory

Mickaël Profeta; Magali Benoit; Francesco Mauri; Chris J Pickard

doi:10.1021/ja0490830

First-principles calculation of the 17O NMR parameters in Ca oxide and Ca aluminosilicates: the partially covalent nature of the Ca-O bond, a challenge for density functional theory

J Am Chem Soc. 2004 Oct 6;126(39):12628-35. doi: 10.1021/ja0490830.

Authors

Mickaël Profeta¹, Magali Benoit, Francesco Mauri, Chris J Pickard

Affiliation

¹ Laboratoire de Minéralogie-Cristallographie de Paris, Université Pierre et Marie Curie, 4, place Jussieu, 75252 Paris Cedex, France.

PMID: 15453796
DOI: 10.1021/ja0490830

Abstract

We apply density functional theory (DFT) to the calculation of the (17)O NMR parameters in Ca and Mg oxides and aluminosilicates. We study the accuracy of the Perdew, Burke, and Ernzerhof (PBE) generalized-gradient approximation to DFT in the description of these systems and the origin of the experimentally observed large dependence of the (17)O chemical shift on the alkaline earth ion. We find that (i) the partially covalent nature of the Ca-O bond has a huge impact on the O chemical shifts. The Ca-O covalence alone explains why in Ca oxides and aluminosilicates the (17)O chemical shifts are much more deshielded than those of the corresponding Mg compounds. (ii) The Ca-O covalence is overestimated by the PBE functional. Thus PBE-DFT is not able to reproduce the measured (17)O NMR parameters in Ca oxide and Ca aluminosilicates. (iii) It is possible to correct for the PBE-DFT deficiency in a simple and transferable way and to predict very accurate (17)O NMR parameters. Such accuracy allows us to assign the (17)O NMR spectra of two important model systems: the grossite aluminate (CaAl(4)O(7)) and the wollastonite (CaSiO(3)) silicate.