Density functional theory calculations of nuclear quadrupole coupling constants with calibrated ¹⁷O quadrupole moments

Abstract

Density functional calculations of the electric field gradient tensor at the oxygen nucleus in O₂, OCS, HNCO, CO, H₂O, H₂CO and C₂H₄O have been performed using the linear combination of Gaussian-type orbital Kohn—Sham density functional theory (LCGTO-KS-DFT) approach. The calculations were of all-electron type using local and gradient corrected functionals. All molecular structures were fully optimized at both levels of theory employing small and extended basis sets. For the calculation of the nuclear quadrupole coupling constants of the molecules studied, calibrated ¹⁷O nuclear quadruple moments were derived for the different basis sets and exchange—correlation functionals. With these calibrated ¹⁷O nuclear quadrupole moments the nuclear quadrupole resonance spectra of organic carbonyl compounds were calculated. The calculated and experimental spectra are in good agreement, therefore making an assignment of structural features possible. This work demonstrates that an accurate prediction of nuclear quadrupole resonance spectra is possible with only modest computational effort using density functional methods in combination with calibrated quadrupole moments.