GIPAW Pseudopotentials of d Elements for Solid-State NMR

Abstract

Computational methods are increasingly used to support interpreting, assigning and predicting the solid-state nuclear resonance magnetic spectra of materials. Currently, density functional theory is seen to achieve a good balance between efficiency and accuracy in solid-state chemistry. To be specific, density functional theory allows the assignment of signals in nuclear resonance magnetic spectra to specific sites and can help identify overlapped or missing signals from experimental nuclear resonance magnetic spectra. To avoid the difficulties correlated to all-electron calculations, a gauge including the projected augmented wave method was introduced to calculate nuclear resonance magnetic parameters with great success in organic crystals in the last decades. Thus, we developed a gauge including projected augmented pseudopotentials of 21 d elements and tested them on, respectively, oxides or nitrides (semiconductors), calculating chemical shift and quadrupolar coupling constant. This work can be considered the first step to improving the ab initio prediction of nuclear magnetic resonance parameters, and leaves open the possibility for inorganic compounds to constitute an alternative standard compound, with respect to tetramethylsilane, to calculate the chemical shift. Furthermore, this work represents the possibility to obtain results from first-principles calculations, to train a machine-learning model to solve or refine structures using predicted nuclear magnetic resonance spectra.

Identification of paramagnetic centers in irradiated Sn-doped silicon dioxide by first-principles

“…The Perdew-Burke-Ernzerhof exchange-correlation functional has been adopted [39]. Normconserving Trouiller-Martins pseudopotentials with gauge including projector augmented wave (GIPAW) reconstruction are used [40,41] and the Kohn-Sham wavefunctions are expanded in a basis of plane waves up to a cutoff energy of 80 Ry. The Γ point was used for sampling the Brillouin zone [42].…”

Theory and computation of nuclear shielding

“…Stepanov et al 143 applied DFT calculations to predict 13 C NMR chemical shifts of selected hydrocarbons adsorbed on Zn-modified zeolites. Ceresoli et al 144 reported on GIPAW pseudopotentials of d-elements for solid-state NMR. Hartman and Harper 145 improved the accuracy of GIPAW chemical shielding calculations with cluster and fragment corrections.…”

Crystal Structure of γ‐Ca2P2O7

“…All fractional atomic coordinates were allowed to relax in P 1 symmetry using pseudopotentials of the kjpaw‐type from the pslibrary (version 1.0) [39] . For the gipaw calculations a single‐point SCF calculation were performed with norm‐conserving Troullier‐Martins type pseudopotentials [40] with PAW reconstruction [41] (X.pbe‐tm‐new‐gipaw‐dc.UPF files (X=P, O); Ca.pbe‐tm‐new‐dc.UPF) [42] . The PBE density functional [43,44] was used and if applicable (see below) non‐empirical van der Waals correction (vdW‐DF [45–48] ).…”

“…[39] For the gipaw calculations a single-point SCF calculation were performed with norm-conserving Troullier-Martins type pseudopotentials [40] with PAW reconstruction [41] (X.pbe-tm-new-gipaw-dc.UPF files (X=P, O); Ca.pbe-tm-new-dc.UPF). [42] The PBE density functional [43,44] was used and if applicable (see below) non-empirical van der Waals correction (vdW-DF [45][46][47][48] ). The convergence threshold for selfconsistency of the electronic wave function was set to 10 À 13 a.u., while the thresholds for the total energy and the atomic forces were set to 10 À 12 a.u.…”