Nuclear Magnetic Resonance Chemical Shifts and Quadrupole Couplings for Different Hydrogen-Bonding Cases Occurring in Liquid Water:  A Computational Study

Abstract

Nuclear magnetic resonance (NMR) parameters are determined theoretically for the oxygen and hydrogen/deuterium nuclei of differently hydrogen-bonded water molecules in liquid water at 300 K. The parameters are the chemical shift, the shielding anisotropy, the asymmetry parameter of shielding, the nuclear quadrupole coupling constant, and the asymmetry parameter of the nuclear quadrupole coupling. We sample instantaneous configurations from a Car-Parrinello molecular dynamics simulation and feed nuclear coordinates into a quantum chemical program for the calculation of NMR parameters using density-functional theory with the three-parameter hybrid exchange-correlation (B3LYP) functional. In the subsequent analysis, molecules are divided into groups according to the number of hydrogen bonds they possess, and the full average NMR tensors are calculated separately for each group. The classification of the hydrogen-bonding cases is performed using a simple distance-based criterion. The analysis reveals in detail how the NMR tensors evolve as the environment changes gradually from gas to liquid upon increasing the number of hydrogen bonds to the molecule of interest. Liquid-state distributions of the instantaneous values of the NMR properties show a wide range of values for each hydrogen-bonding species with significant overlap between the different cases. Our study shows how local changes in the environment, along with classical thermal averaging, affect the NMR parameters in liquid water. For example, a broken or alternatively extra hydrogen bond induces major changes in the NMR tensors, and the effect is more pronounced for hydrogen or deuterium than for oxygen. The data sheds light on the usefulness of NMR experiments in investigating the local coordination of liquid water.

NMR chemical shifts as a tool to analyze first principles molecular dynamics simulations in condensed phases: the case of liquid water

“…The only computationally efficient way to compute spectroscopic parameters for complex liquids using hybrid and meta‐GGA functionals consists of extracting trajectory snapshots from a Car–Parrinello molecular dynamics simulation and feeding them into a separate quantum chemistry package. This has been done by the Vaara group for liquid water 37, 38. Their results show that this method has the potential to be very accurate, but it requires the combination of two distinct codes.…”

Computing the 1H NMR Spectrum of a Bulk Ionic Liquid from Snapshots of Car–Parrinello Molecular Dynamics Simulations

“…On the other hand, the question of whether NMR properties can be predicted at all in static structures (such as those typically dealt with in computational chemistry) is emerging as a novel area of investigation 38. Indeed, it has been shown that in many cases, success can be attained only by going beyond static molecules,39–42 that is, dealing not only with the species of interest, but with the environment and its dynamics as well.…”

Hydrophobic signature on TiO2 nanoparticles in liquid water

“…1 H chemical shifts are sensitive to the number of hydrogen bonds and the structure of the developed hydrogenbonded network of H2O molecules. 42 Also, to geometrical constraints and confinement effects at the material surface. 43 To shed light on the chemical nature of protons contributing to the 1 H NMR signals in the 0-2.1 ppm region, chemical shifts histograms resulting from our MD-DFT/GIPAW calculations obtained for the four scenarios of adsorbed water molecules and hydroxyl groups have been prepared.…”