Polarization model for water and its ionic dissociation products
15 Aug 1978-Journal of Chemical Physics (American Institute of Physics)-Vol. 69, Iss: 4, pp 1473-1484
TL;DR: In this paper, a new model was constructed which treated H+ and O2− particles as the basic dynamical and structural elements, and the model yields water molecules which have the correct geometry and dipole moment, and which engage in hydrogen bonding to one another.
Abstract: In order to achieve a simple description of aggregates of deformable water molecules, a new model has been constructed which treats H+ and O2− particles as the basic dynamical and structural elements. The H+ units are bare protons, while the O2− units possess a form of nonlocal polarizability consistent with their electronic structure. The model yields water molecules which have the correct geometry and dipole moment, and which engage in hydrogen bonding to one another. Minimum‐energy structures have been determined for the water dimer and trimer and for small hydrate clusters of H+ and OH−; comparison with relevant experiments and quantum–mechanical calculations is satisfactory.
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TL;DR: The chapter focuses on a general description of the force fields that are most commonly used at present and gives an indication of the directions of current research that may yield better functions in the near future.
Abstract: Publisher Summary The chapter focuses on a general description of the force fields that are most commonly used at present, and it gives an indication of the directions of current research that may yield better functions in the near future. After a brief survey of current models, mostly generated during the 1990s, the focus of the chapter is on the general directions the field is taking in developing new models. The most commonly used protein force fields incorporate a relatively simple potential energy function: The emphasis is on the use of continuum methods to model the electrostatic effects of hydration and the introduction of polarizability to model the electronic response to changes in the environment. Some of the history and performance of widely used protein force fields based on an equation on simplest potential energy function or closely related equations are reviewed. The chapter outlines some promising developments that go beyond this, primarily by altering the way electrostatic interactions are treated. The use of atomic multipoles and off-center charge distributions, as well as attempts to incorporate electronic polarizability, are also discussed in the chapter.
1,743 citations
Cites background from "Polarization model for water and it..."
...An interesting polarizable and dissociable potential was suggested by Stillinger and David (1978) and applied to water clusters and ion monohydrates....
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TL;DR: In this article, a new molecular dynamics model in which the point charges on atomic sites are allowed to fluctuate in response to the environment is developed and applied to water, based on the concept of electronegativity equalization.
Abstract: A new molecular dynamics model in which the point charges on atomic sites are allowed to fluctuate in response to the environment is developed and applied to water. The idea for treating charges as variables is based on the concept of electronegativity equalization according to which: (a) the electronegativity of an atomic site is dependent on the atom’s type and charge and is perturbed by the electrostatic potential it experiences from its neighbors and (b) charge is transferred between atomic sites in such a way that electronegativities are equalized. The charges are treated as dynamical variables using an extended Lagrangian method in which the charges are given a fictitious mass, velocities, and kinetic energy and then propagated according to Newtonian mechanics along with the atomic degrees of freedom. Models for water with fluctuating charges are developed using the geometries of two common fixed‐charge water potentials: the simple point charge (SPC) and the four‐point transferable intermolecular po...
1,121 citations
TL;DR: A review of the most popular methods for combined quantum mechanical/molecular mechanical (QM/MM) calculations, including their advantages and disadvantages, can be found in this article.
Abstract: This paper briefly reviews the current status of the most popular methods for combined quantum mechanical/molecular mechanical (QM/MM) calculations, including their advantages and disadvantages There is a special emphasis on very general link-atom methods and various ways to treat the charge near the boundary Mechanical and electric embedding are contrasted We consider methods applicable to gas-phase organic chemistry, liquid-phase organic and organometallic chemistry, biochemistry, and solid-state chemistry Then we review some recent tests of QM/MM methods and summarize what we learn about QM/MM from these studies We also discuss some available software Finally, we present a few comments about future directions of research in this exciting area, where we focus on more intimate blends of QM with MM
1,045 citations
TL;DR: The purpose is to appraise what have been accomplished during all these years of model potentials publication and testing and what deserves to be improved and to give some guidance for future investigations.
924 citations
TL;DR: A test is proposed in which 17 properties of water, from the vapour and liquid to the solid phases, are taken into account to evaluate the performance of a water model, being quantitative and selecting properties from all phases of water can be useful in the future to identify progress in the modelling of water.
Abstract: Over the last forty years many computer simulations of water have been performed using rigid non-polarizable models. Since these models describe water interactions in an approximate way it is evident that they cannot reproduce all of the properties of water. By now many properties for these kinds of models have been determined and it seems useful to compile some of these results and provide a critical view of the successes and failures. In this paper a test is proposed in which 17 properties of water, from the vapour and liquid to the solid phases, are taken into account to evaluate the performance of a water model. A certain number of points between zero (bad agreement) and ten (good agreement) are given for the predictions of each model and property. We applied the test to five rigid non-polarizable models, TIP3P, TIP5P, TIP4P, SPC/E and TIP4P/2005, obtaining an average score of 2.7, 3.7, 4.7, 5.1, and 7.2 respectively. Thus although no model reproduces all properties, some models perform better than others. It is clear that there are limitations for rigid non-polarizable models. Neglecting polarizability prevents an accurate description of virial coefficients, vapour pressures, critical pressure and dielectric constant. Neglecting nuclear quantum effects prevents an accurate description of the structure, the properties of water below 120 K and the heat capacity. It is likely that for rigid non-polarizable models it may not be possible to increase the score in the test proposed here beyond 7.6. To get closer to experiment, incorporating polarization and nuclear quantum effects is absolutely required even though a substantial increase in computer time should be expected. The test proposed here, being quantitative and selecting properties from all phases of water can be useful in the future to identify progress in the modelling of water.
810 citations
References
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Book•
01 Jan 1969
TL;DR: The Water Molecule 2 The Real Vapour 3. Ice 4. Properties of Liquid Water 5. Models for Liquid Water Addendum as mentioned in this paper, which is an extension of the model presented in this paper.
Abstract: 1. The Water Molecule 2. The Real Vapour 3. Ice 4. Properties of Liquid Water 5. Models for Liquid Water Addendum
2,886 citations
TL;DR: In this paper, a four-charge model for each molecule and a modification of the prior ''BNS'' interaction was proposed to improve the fidelity of the molecular dynamics simulation, leading to a density maximum near 27°C for the liquid in coexistence with its vapor and to molecular distribution functions in better agreement with x-ray scattering experiments.
Abstract: Molecular dynamics calculations on a classical model for liquid water have been carried out at mass density 1 g/cm3 and at four temperatures. The effective pair potential employed is based on a four‐charge model for each molecule and represents a modification of the prior ``BNS'' interaction. Results for molecular structure and thermodynamic properties indicate that the modification improves the fidelity of the molecular dynamics simulation. In particular, the present version leads to a density maximum near 27°C for the liquid in coexistence with its vapor and to molecular distribution functions in better agreement with x‐ray scattering experiments.
1,551 citations
TL;DR: In this paper, the authors used electric resonance spectroscopy (ES) to study hydrogen-bonded water dimers, generated in a supersonic nozzle, and found that the resulting structure is consistent with a linear hydrogen bond and the proton acceptor tetrahedrally oriented to the hydrogen bond.
Abstract: Molecular beams of hydrogen bonded water dimer, generated in a supersonic nozzle, have been studied using electric resonance spectroscopy. Radiofrequency and microwave transitions have been observed in (H2 16O)2, (D2 16O)2, and (H2 18O)2. Transitions arising from both pure rotation and rotation–tunneling occur. The pure rotational transitions have been fit to a rigid rotor model to obtain structural information. Information on the relative orientation of the two monomer units is also contained in the electric dipole moment component along the A inertial axis μa, which is obtained from Stark effect measurements. The resultant structure is that of a ’’trans‐linear’’ complex with an oxygen–oxygen distance ROO of 2.98(1) A, the proton accepting water axis is 58(6) ° with respect to ROO, and the proton donating water axis at −51(6) ° with respect to ROO. This structure is consistent with a linear hydrogen bond and the proton acceptor tetrahedrally oriented to the hydrogen bond. The limits of uncertainty are wh...
665 citations
TL;DR: In this paper, the potential of interaction for pairs and triplets of water molecules was investigated, and the most stable pair configuration involves a linear hydrogen bond of length ROO = 3.00 A and strength 4.72 kcal/mole.
Abstract: Accurate SCF calculations have been carried out to investigate the potential of interaction for pairs and triplets of water molecules. The most stable pair configuration involves a linear hydrogen bond of length ROO = 3.00 A and strength 4.72 kcal/mole. Three‐molecule nonadditivities are large in magnitude and vary in sign according to the hydrogen‐bond pattern involved. In both aqueous liquids and solids, the net trimer nonadditivity effect amounts to increased binding energy, decreased neighbor distance, and slightly enhanced tendency toward perfect tetrahedral coordination symmetry. The nonadditivity furthermore is inconsistent with the phenomenology of simple mutual electrostatic polarization between neighboring molecules.
514 citations