EFGShield — A program for parsing and summarizing the results of electric field gradient and nuclear magnetic shielding tensor calculations

Abstract

A computer program (EFGShield) is described that simplifies and summarizes the output from electric field gradient (EFG) and nuclear magnetic shielding tensor calculations performed independently using existing quantum chemical software. In addition to summarizing tensor magnitudes according to conventions commonly used by solid-state NMR spectroscopists, the program provides Euler angles relating the orientations of the EFG and shielding tensor principal axis systems (PAS). An atomic coordinate file is generated that also contains dummy atoms representing the orientations of the EFG and shielding tensor PASs in the molecular framework. We demonstrate the functionality of the program using calculations of the chlorine EFG and shielding tensors for strontium chloride dihydrate and calcium chloride dihydrate. Several models of the chloride environment in these compounds are tested, including those where point charges are used to represent the extended three-dimensional lattices within the self-consistent charge field perturbation approach. The results highlight both the shortcomings and successes of traditional localized orbital-based basis sets in the description of the NMR properties of extended systems. We anticipate that EFGShield will be a useful tool for spectroscopists using quantum chemical software to aid in the interpretation of experimental data.Key words: quantum chemical calculations, computer program, electric field gradient tensor, quadrupolar coupling constant, nuclear magnetic shielding tensor, Euler angles, alkaline earth chloride hydrates.

Crystal Structure Based Design of Signal Enhancement Schemes for Solid-State NMR of Insensitive Half-Integer Quadrupolar Nuclei

“…Euler angles were determined using EFGShield. 32 These parameters were used to optimize the 33 S NMR experiments.…”

Probing the Local Structure of Pure Ionic Liquid Salts with Solid‐ and Liquid‐State NMR

“…The chlorine EFG and shielding tensors generated in the Gaussian output files were then analyzed using the EFGShield program (version 2.2). [26] The resulting parameters are tabulated along with their experimental counterparts in Table 4.…”

Testing the sensitivity limits of 33S NMR: An ultra-wideline study of elemental sulfur

“…Perdew, Burke and Ernzerhof functionals were used with plane wave basis set cut-offs and Monkhorst-Pack k-space grid sizes set automatically under a ''fine" basis set accuracy. The CASTEP calculations also provided values for the CSA parameters (Table 1) and the relative orientations of the EFG and CSA tensors (extracted using EFGShield [27]). The EFG tensor orientation is shown in Fig.…”