title: Accurate First-Principle Prediction of (29)Si and (17)O NMR Parameters in SiO2 Polymorphs: The Cases of Zeolites Sigma-2 and Ferrierite.
abstract: The magnetic shielding tensors of silica polymorphs have been investigated by means of quantum chemical calculations. Several levels of theory, from Hartree-Fock to the last generation of Density Functional Theory based approaches, have been tested on predicting (29)Si and (17)O isotropic and principal components of the chemical shift tensors together with (17)O quadrupolar coupling constants. The NMR parameters have been computed on all known silica systems, namely, α-quartz, α-cristobalite, coesite, Sigma-2, and ferrierite zeolites. Besides, cluster based approaches have been compared to a hybrid Quantum-Mechanics/Molecular-Mechanics (QM/MM) method, within the ONIOM scheme. The convergence of computed (17)O NMR parameters with respect to cluster size is found to be system-dependent. Excellent agreement between computed and experimental data has been found for (29)Si NMR parameters of the different Si sites of silica polymorphs and of Sigma-2 and ferrierite zeolites.
authors.affiliation: Dipartimento di Chimica, Università di Modena e Reggio Emilia, Via G. Campi 183, 41100 Modena, Italy, Dipartimento di Chimica "Paolo Corradini" and CR-INSTM "Village", Università di Napoli Federico II, Complesso Universitario Monte Sant'Angelo Via Cintia I, 80126, Napoli, Italy, and Istituto per i Processi Chimico Fisici CNR and CR-INSTM "Village", Area della Ricerca del CNR Via Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Pedone
authors.affiliation: Dipartimento di Chimica, Università di Modena e Reggio Emilia, Via G. Campi 183, 41100 Modena, Italy, Dipartimento di Chimica "Paolo Corradini" and CR-INSTM "Village", Università di Napoli Federico II, Complesso Universitario Monte Sant'Angelo Via Cintia I, 80126, Napoli, Italy, and Istituto per i Processi Chimico Fisici CNR and CR-INSTM "Village", Area della Ricerca del CNR Via Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Pavone
authors.affiliation: Dipartimento di Chimica, Università di Modena e Reggio Emilia, Via G. Campi 183, 41100 Modena, Italy, Dipartimento di Chimica "Paolo Corradini" and CR-INSTM "Village", Università di Napoli Federico II, Complesso Universitario Monte Sant'Angelo Via Cintia I, 80126, Napoli, Italy, and Istituto per i Processi Chimico Fisici CNR and CR-INSTM "Village", Area della Ricerca del CNR Via Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Menziani
authors.affiliation: Dipartimento di Chimica, Università di Modena e Reggio Emilia, Via G. Campi 183, 41100 Modena, Italy, Dipartimento di Chimica "Paolo Corradini" and CR-INSTM "Village", Università di Napoli Federico II, Complesso Universitario Monte Sant'Angelo Via Cintia I, 80126, Napoli, Italy, and Istituto per i Processi Chimico Fisici CNR and CR-INSTM "Village", Area della Ricerca del CNR Via Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Barone