The ability of simple potential functions to reproduce accurately the density of liquid water from −37 to 100 °C at 1 to 10 000 atm has been further explored. The result is the five-site TIP5P model, which yields significantly improved results; the average error in the density over the 100° temperature range from −37.5 to 62.5 °C at 1 atm is only 0.006 g cm−3. Classical Monte Carlo statistical mechanics calculations have been performed to optimize the parameters, especially the position of the negative charges along the lone-pair directions. Initial calculations with 216 molecules in the NPT ensemble at 1 atm focused on finding a model that reproduced the shape of the liquid density curve as a function of temperature. Calculations performed for 512 molecules with the final TIP5P model demonstrate that the density maximum near 4 °C at 1 atm is reproduced, while high-quality structural and thermodynamic results are maintained. Attainment of high precision for the low-temperature runs required sampling for more than 1 billion Monte Carlo configurations. In addition, the dielectric constant was computed from the response to an applied electric field; the result is 81.5±1.5 at 25 °C and the experimental curve is mirrored from 0–100 °C at 1 atm. The TIP5P model is also found to perform well as a function of pressure; the density of liquid water at 25 °C is reproduced with an average error of ∼2% over the range from 1 to 10 000 atm, and the shift of the temperature of maximum density to lower temperature with increasing pressure is also obtained.

/pdf/a-five-site-model-for-liquid-water-and-the-reproduction-of-4waghhehgx.pdf

A five-site model for liquid water and the reproduction of the density anomaly by rigid, nonpolarizable potential functions

A re-parameterization of the standard TIP4P water model for use with Ewald techniques is introduced, providing an overall global improvement in water properties relative to several popular nonpolarizable and polarizable water potentials. Using high precision simulations, and careful application of standard analytical corrections, we show that the new TIP4P-Ew potential has a density maximum at approximately 1 degrees C, and reproduces experimental bulk-densities and the enthalpy of vaporization, DeltaH(vap), from -37.5 to 127 degrees C at 1 atm with an absolute average error of less than 1%. Structural properties are in very good agreement with x-ray scattering intensities at temperatures between 0 and 77 degrees C and dynamical properties such as self-diffusion coefficient are in excellent agreement with experiment. The parameterization approach used can be easily generalized to rehabilitate any water force field using available experimental data over a range of thermodynamic points.

/pdf/development-of-an-improved-four-site-water-model-for-10rw432kke.pdf

Development of an improved four-site water model for biomolecular simulations: TIP4P-Ew

The collection of extensive, reliable, oceanic carbon data is a key component of the Joint Global Ocean Flux Study (JGOFS). A portion of the US JGOFS oceanic carbon dioxide measurements will be made during the World Ocean Circulation Experiment Hydrographic Program. A science team has been formed to plan and coordinate the various activities needed to produce high quality oceanic carbon dioxide measurements under this program. This handbook was prepared at the request of, and with the active participation of, that science team. The procedures have been agreed on by the members of the science team and describe well tested methods. They are intended to provide standard operating procedures, together with an appropriate quality control plan, for measurements made as part of this survey. These are not the only measurement techniques in use for the parameters of the oceanic carbon system; however, they do represent the current state-of-the-art for ship-board measurements. In the end, the editors hope that this handbook can serve widely as a clear and unambiguous guide to other investigators who are setting up to analyze the various parameters of the carbon dioxide system in sea water.

/pdf/handbook-of-methods-for-the-analysis-of-the-various-29uh3pds0b.pdf

Handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water. Version 2

The anomalous properties of cold and supercooled water, such as the fact that at sufficiently low temperatures it becomes more compressible and less dense when cooled, and more fluid when compressed, have attracted the attention of physical scientists for a long time. The discovery in the 1970s that several thermodynamic and transport properties of supercooled water exhibit a pronounced temperature dependence and appear to diverge slightly below the homogeneous nucleation temperature inspired a large number of experimental and theoretical studies. Likewise, an important body of work on glassy water has been stimulated by experiments, starting in the mid-1980s and continuing to this date, which suggest that vitreous water can exist in at least two apparently distinct forms. A coherent theory of the thermodynamic and transport properties of supercooled and glassy water does not yet exist. Nevertheless, significant progress towards this goal has been made during the past 20 years. This article summarizes the known experimental facts and reviews critically theoretical and computational work aimed at interpreting the observations and providing a unified viewpoint on cold, non-crystalline, metastable states of water.

https://iopscience.iop.org/article/10.1088/0953-8984/15/45/R01/pdf

Supercooled and glassy water

A series of Monte Carlo simulations has been carried out to characterize the temperature and size dependence of the results for liquid water using the TIP4P potential function. Five temperatures from -25 to 100°C and four system sizes from 64 to 512 molecules have been studied. Comparisons are made with experimental thermodynamic and structural data as well as results of prior simulations.

Temperature and size dependence for Monte Carlo simulations of TIP4P water

A review is given of the temperature dependence of the density of liquid water from 40" to 150°C The inclusion of new literature data indicates that most previous correlations have been 10 ppm low at 70-80°C An expression is derived, Equation 16, expressed on the IPTS-68 and valid from 0" to 150"C, that is in improved agreement with most data sets Recent literature values of the velocity of sound permit the calculation of more reliable isothermal compressibilities The errors of these compressibilities;, from velocity of sound, density, thermal expansivity, and specific heat, are examined, and the error in the calculated compressibilities is estimated as 03 X lO-'bar-' at 4'C and as7 X 100°C This paper supersedes two papers previously given by the same author The revision of correlating and interpolating equations, and of estimated best values and their errors, must be repeated whenever standards are modified or a significant addition is made to the pool of experimental data At atmospheric pressure (=101325 bar), the volume or density, the thermal expansivity, and the compressibility are among the properties of liquid water that are known with sufficient precision for the introduction of the 1968 lnternational Practical Temperature Scale (72) to make it

Density, thermal expansivity, and compressibility of liquid water from 0° to 150°C: correlations and tables for atmospheric pressure and saturation reviewed and expressed on 1968 temperature scale.

George S. Kell

Papers

Density, thermal expansivity, and compressibility of liquid water from 0° to 150°C: correlations and tables for atmospheric pressure and saturation reviewed and expressed on 1968 temperature scale.

Isothermal compressibility of liquid water at 1 atm.

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