Molecular dynamics simulation of the dielectric constant of water: The effect of bond flexibility

Abstract

The role of bond flexibility on the dielectric constant of water is investigated via molecular dynamics simulations using a flexible intermolecular potential SPC/Fw [Y. Wu, H. L. Tepper, and G. A. Voth, J. Chem. Phys. 128, 024503 (2006)]. Dielectric constants and densities are reported for the liquid phase at temperatures of 298.15 K and 473.15 K and the supercritical phase at 673.15 K for pressures between 0.1 MPa and 200 MPa. Comparison with both experimental data and other rigid bond intermolecular potentials indicates that introducing bond flexibility significantly improves the prediction of both dielectric constants and pressure-temperature-density behavior. In some cases, the predicted densities and dielectric constants almost exactly coincide with experimental data. The results are analyzed in terms of dipole moments, quadrupole moments, and equilibrium bond angles and lengths. It appears that bond flexibility allows the molecular dipole and quadrupole moment to change with the thermodynamic state point, and thereby mimic the change of the intermolecular interactions in response to the local environment.

Molecular dynamics simulations for the prediction of the dielectric spectra of alcohols, glycols and monoethanolamine

“…Previous work has shown the importance of selecting the appropriate block length for the correct calculation of this property of water [94,95]. This is confirmed by the results shown in Fig.…”

“…16) to calculate the static dielectric constant, for the force fields showing a better performance in the prediction of the dielectric spectrum in every case (water SPC, ethanol TraPPE.UA, ethylene glycol OPLS, propylene glycol GAFF, glycerol OPLS and MEA OPLS). Black circles represent experimental values obtained from different sources for the following systems: water [9.12], ethanol [16.18, 97], ethylene glycol [98], propylene glycol [99], glycerol [95,96,100,101] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 …”

Fluctuations of local electric field and dipole moments in water between metal walls

“…(42) at ∆Φ = 0 (see Fig.15(b) in Appendix D), which yields χ = 4.68 and = 59.8 from Eq.(41). Now, in addition to this derivation, we have determined ε from the dielectric relation (21) 27 and from the data of M 2 z 0 and w (see the sentence below Eq. (22)…”

“…i) We should examine how the dipole and the local field move together in rotational big jumps in liquid water 27,40 . ii) We should consider the molecular polarizability due to molecular stretching in strong local field 21,22 . iii) Ions strongly influence the local fields of the surrounding water molecules 35 , resulting in a hydration shell around each ion, so this aspect should further be studied.…”

“…In molecular dynamics simulations [10][11][12][13][14][15][16][17][18][19][20][21][22] , ε has been calculated on the basis of its linear response expressions under the three-dimensional (3D) periodic boundary condition. In such studies, the Ewald method has been used to efficiently sum the electrostatic interactions 12,14 .…”