Erratum: Intermolecular Dynamical Charge Fluctuations in Water: A Signature of the H-Bond Network [Phys. Rev. Lett.<b>95</b>, 187401 (2005)]

102

Anions populate fluid interfaces specifically. Here, we report experiments showing that on hydrogenbonded interfaces anions interact specifically over unexpectedly long distances. The composition of binary electrolyte (Na + , X − /Y − ) films was investigated as a function of solvent, film thickness, and third ion additions in free-standing films produced by blowing up drops with a high-speed gas. These films soon fragment into charged sub-micrometer droplets carrying excess anions detectable in situ by online electrospray ionization mass spectrometry. We found that (1) the larger anions are enriched in the thinner (nanoscopic air-liquid-air) films produced at higher gas velocities in all (water, methanol, 2-propanol, and acetonitrile) tested solvents, (2) third ions (beginning at sub-μM levels) specifically perturb X − /Y − ratios in water and methanol but have no effect in acetonitrile or 2-propanol. Thus, among these polar organic liquids (of similar viscosities but much smaller surface tensions and dielectric permittivities than water) only on methanol do anions interact specifically over long, viz.: r i − r j /nm = 150 (c/μM) −1/3 , distances. Our findings point to the extended hydrogenbond networks of water and methanol as likely conduits for such interactions. © 2013 AIP Publishing LLC. [http://dx

Section: Resultsmentioning

confidence: 78%

Long-range specific ion-ion interactions in hydrogen-bonded liquid films

Enami

Colussi

2013

102

“…That band is better represented in more sophisticated polarizable models of water, [43][44][45] presumably since those are polarizable also at the hydrogen sites and as such feel more closely the formation of a hydrogen bond, or since those are flexible models. It is however very well established that this band originates from charge flows between water molecules upon hydrogen bonding, 5,[36][37][38][39] and it is quite questionable whether polarizability can describe that effect. The electric field at a polarizable site scales decays quadratically with the distance to an hydrogen bond partner, whereas charge flow effects decrease much steeper with an exponential dependence.…”

Section: Discussionmentioning

confidence: 99%

“…32 It is well established that simple point charge models of water, such as TIP4P/2005 34 or SPC/E, 35 cannot account for the intensity of that band, since that band originates from charge flows within and between water molecules upon hydrogen bonding. 5,[36][37][38][39] Adding polarizability to a water model, either in an ad hoc manner to a trajectory that has been precalculated with the help of a pointcharge model, [39][40][41][42] or explicitly as part of the force field, [43][44][45] reveals the band in the THz absorption spectrum, albeit, often, with severely underestimated intensity.…”

Section: Introductionmentioning

confidence: 99%

2D-Raman-THz spectroscopy: A sensitive test of polarizable water models

Hamm

2014

In a recent paper, the experimental 2D-Raman-THz response of liquid water at ambient conditions has been presented [J. Savolainen, S. Ahmed, and P. Hamm, Proc. Natl. Acad. Sci. U. S. A. 110, 20402 (2013)]. Here, all-atom molecular dynamics simulations are performed with the goal to reproduce the experimental results. To that end, the molecular response functions are calculated in a first step, and are then convoluted with the laser pulses in order to enable a direct comparison with the experimental results. The molecular dynamics simulation are performed with several different water models: TIP4P/2005, SWM4-NDP, and TL4P. As polarizability is essential to describe the 2D-Raman-THz response, the TIP4P/2005 water molecules are amended with either an isotropic or a anisotropic polarizability a posteriori after the molecular dynamics simulation. In contrast, SWM4-NDP and TL4P are intrinsically polarizable, and hence the 2D-Raman-THz response can be calculated in a self-consistent way, using the same force field as during the molecular dynamics simulation. It is found that the 2D-Raman-THz response depends extremely sensitively on details of the water model, and in particular on details of the description of polarizability. Despite the limited time resolution of the experiment, it could easily distinguish between various water models. Albeit not perfect, the overall best agreement with the experimental data is obtained for the TL4P water model. © 2014 AIP Publishing LLC. [http://dx

“…101 In this regard, maximally localized Wannier functions (MLWFs), which are obtained via a unitary transformation of the occupied Kohn-Sham electronic states, have been shown to be an extremely useful tool in computing molecular dipole moments in condensed-phase environments. 35,[102][103][104][105] For the case of liquid water, the MLWFs associated with different molecules have only a very minor overlap, 102 and this fact allows for a nearly unique definition of the charges belonging to a given water molecule, thereby eliminating to a large extent the aforementioned partitioning issues when computing molecular dipole moments in the condensed-phase.…”

Section: F Dipole Moment Analysis In Liquid Watermentioning

confidence: 99%

The individual and collective effects of exact exchange and dispersion interactions on the ab initio structure of liquid water

DiStasio

Santra

et al. 2014

Self Cite

329

404

In this work, we report the results of a series of density functional theory (DFT) based ab initio molecular dynamics (AIMD) simulations of ambient liquid water using a hierarchy of exchange-correlation (XC) functionals to investigate the individual and collective effects of exact exchange (Exx), via the PBE0 hybrid functional, non-local vdW/dispersion interactions, via a fully self-consistent density-dependent dispersion correction, and approximate nuclear quantum effects (aNQE), via a 30 K increase in the simulation temperature, on the microscopic structure of liquid water. Based on these AIMD simulations, we found that the collective inclusion of Exx, vdW, and aNQE as resulting from a large-scale AIMD simulation of (H2O)128 at the PBE0+vdW level of theory, significantly softens the structure of ambient liquid water and yields an oxygen-oxygen structure factor, SOO(Q), and corresponding oxygen-oxygen radial distribution function, gOO(r), that are now in quantitative agreement with the best available experimental data. This level of agreement between simulation and experiment as demonstrated herein originates from an increase in the relative population of water molecules in the interstitial region between the first and second coordination shells, a collective reorganization in the liquid phase which is facilitated by a weakening of the hydrogen bond strength by the use of the PBE0 hybrid XC functional, coupled with a relative stabilization of the resultant disordered liquid water configurations by the inclusion of nonlocal vdW/dispersion interactions. This increasingly more accurate description of the underlying hydrogen bond network in liquid water obtained at the PBE0+vdW+aNQE level of theory yields higher-order correlation functions, such as the oxygen-oxygen-oxygen triplet angular distribution, POOO(θ), and therefore the degree of local tetrahedrality, as well as electrostatic properties, such as the effective molecular dipole moment, that are also in much better agreement with experiment.