Use of molecular dynamics simulations with ab initio SCF calculations for the determination of the deuterium quadrupole coupling constant in liquid water and bond lengths in ice

Abstract

The deuterium quadrupole coupling constant and asymmetry parameter in heavy water were determined using ab initio SCF calculations. Snapshots from a molecular dynamics simulation were used to give liquid water cluster configurations and the influence of simulation parameters on the quadrupole coupling constant was investigated. The electronic potential model and the number of molecules in the molecular dynamics simulation and the pressure of the system were found to have only a small influence on the quadrupole coupling constant. The average value of the quadrupole coupling constant at room temperature, corrected for the known deficiency of the ab initio calculation in the gas phase, yields a quadrupole coupling constant of 253 kHz, in perfect agreement with the most recent experiments. The oxygen-deuterium bond lengths in ice Ih, ice 11, and ice IX were determined using experimental quadrupole coupling constants and a model equation. An averaged bond length of 98.9 pm was obtained for the Ih form, which is approximately 2 pm shorter than that determined by neutron diffraction studies, whereas the bond lengths for the four deuterium sites in ice I1 and the three sites in ice IX are in fair agreement with experiment. 0 1993 by John Wiley & Sons, Inc.

Calculation of Quadrupole Coupling Constants: From Gas to Liquid

“…T here is a small b u t significant positive tem p eratu re dependence, which is a new finding. A sim ilar b ehaviour w as found for the pressure dependence [7]. A further and m ore surprising finding is given in the last colum n of Table 3.…”

“…F igure 10 co m p ares calculated w ith experim ental results at dif ferent tem peratures. D etails of the calculations were published previously [6,7].…”

“…We will p o in t o u t a m odel for D couplings [2] an d a tran sfo rm atio n p roblem [10], know ledge of w hich m ight be of som e interest to the experim entalist. In a second p art, a new ap p ro a ch to calculate D [6,7] an d 170 [8] couplings o f liquid w ater will be discussed. In this, configurations of b ulk w ater are p rod u ced in a m olecular dynam ics sim ulation.…”

Nuclear Spin Relaxation Parameters of MRI Contrast Agents – Insight from Quantum Mechanical Calculations

“…This can be achieved by a conjunction of molecular dynamics simulations with quantum chemical calculations. [49,[55][56][57] MD simulations (Figure 3) can be performed by using one of the empirical force fields available or with a first-prinwww.eurjic.org ciples MD method such as the density-functional-theorybased Car-Parrinello molecular dynamics (CPMD) method. [58] On one hand, density functional theory tends to overstructure liquid water, [59,60] and on the other hand, CPMD is more suitable for the description of coordination compounds than classical MD based on empirical force fields.…”

How approximate is the experimental evaluation of quadrupole coupling constants in liquids? A novel computational study

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