Exploring Systematic Discrepancies in DFT Calculations of Chlorine Nuclear Quadrupole Couplings

Abstract

Citation for published item:ohD ynd § rej nd rodgkinsonD ul nd iddi(eldD gory wF nd tesD tonthn F nd hr § ¡ %nsk¡ yD wrtin @PHIUA 9ixploring systemti disrepnies in hp lultions of hlorine nuler qudrupole ouplingsF9D tournl of physil hemistry eFD IPI @PIAF ppF RIHQERIIQF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACT: Previous studies revealed significant discrepancies between DFT-calculated and experimental nuclear quadrupolar coupling constants (C Q ) at chlorine atoms, particularly in ionic solids. Various aspects of the computations are systematically investigated here, including the choice of the DFT functional, basis set convergence, and geometry optimization protocol. The effect of fast (fs) time-scale dynamics are probed using molecular dynamics (MD) and nuclear quantum effects (NQEs) are considered using path-integral MD calculations. It is shown that the functional choice is the most important factor related to improving the accuracy of the 2 quadrupolar coupling calculations and functionals beyond the generalized gradient approximation (GGA) level, such as hybrid and meta-GGA functionals, are required for good correlations with experiment. The influence of molecular dynamics and NQEs is less important than the functional choice in the studied systems. A method which involves scaling the calculated quadrupolar coupling constant is proposed here; its application leads to good agreement with experimental data.

A Review on Combination of Ab Initio Molecular Dynamics and NMR Parameters Calculations

“…These results concerning the quadrupolar couplings are consistent with the ones obtained in another study from 2017 [ 65 ]. There, the discrepancies in DFT calculations of chlorine nuclear quadrupolar coupling constant for ionic chlorides in crystalline systems were thoroughly investigated.…”

Effects of Li Confined Motion on NMR Quadrupolar Interactions: A Combined 7Li NMR and DFT‐MD Study of LiR2(PO4)3 (R=Ti or Zr) Phases

“…Comparing static and dynamical calculations, we find a decrease in C Q of 18 % (LT Zr phase). Such a difference is larger than any reported in previous works analyzing dynamical effects on quadrupolar parameters . Moreover, in the systems previously studied no increment in the C Q was found, whereas we reproduce for the Ti phase the experimentally observed increment in C Q of more than 100 % at 300 K and more than 200 % at 450 K. In the case of the HT Zr phase, MD simulations not only predict a considerable decrease in C Q (from 19 % to 38 % depending on the starting model used in the MD simulation), but simultaneously explain a drastic change in the η Q value: from about 1 for static structures to about 0 owing to the dynamics of the system.…”

“…Such ad ifference is larger than any reported in previous works analyzing dynamical effectso nq uadrupolar parameters. [8,17] Moreover,i n the systemsp reviously studied no increment in the C Q was found, whereas we reproduce for the Ti phase the experimentally observed increment in C Q of more than 100 %a t3 00 K and more than 200 %a t4 50 K. In the case of the HT Zr phase, MD simulations not only predict ac onsiderable decrease in C Q (from 19 %t o3 8% depending on the starting model used in the MD simulation), but simultaneously explain ad rastic change in the h Q value:f rom about 1f or static structures to about 0o wing to the dynamicso ft he system. Although longrange Li motion above 330 Ki nt he Ti phase has been reported, [14] our simulations showt hat at the considered temperatures the main dynamical effects on the 7 Li quadrupolari nteraction are caused by the confined thermalm otion of Li ions, which is more ubiquitous and likely than jumpsb etween cavities.…”

Perspective: Current advances in solid-state NMR spectroscopy

“…44 Indeed, the difficulty of locating H atoms in XRD studies means that NMR crystallography can be an effective means of identifying incorrect structures; see, for example, Ref. 45 and references therein. For many molecular systems, optimization of atomic coordinates (either of H or of all atoms) is typically carried out with lattice parameters fixed at their values determined by diffraction.…”