Properties of liquid water from a systematic refinement of a high-rank multipolar electrostatic potential (original) (raw)
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Journal of Chemical Theory and Computation, 2008
We propose a new rigid, nonpolarizable high-rank multipolar potential for the simulation of liquid water. The electrostatic interaction is represented by spherical tensor multipole moments on oxygen and hydrogen, up to hexadecupole. The Quantum Chemical Topology (QCT) method yields the atomic multipole moments from a MP2/aug-cc-p-VTZ electron density of a single water molecule in the gas phase. These moments reproduce the experimental molecular dipole and quadrupole moment within less than 1%. Given its high-rank multipole moments, used in conjunction with a consistent high-rank multipolar Ewald summation, the QCT potential is ideal to assess the performance of exhaustive "gas phase" electrostatics in molecular dynamics simulations of liquids. The current article explores the performance of this potential at 17 temperatures between -35°C (238 K) and 90°C (363 K) and at 7 pressures between 1 and 10 000 atm. The well-known maximum in the liquid's density at 4°C is reproduced at 6°C. Six bulk properties are calculated and found to deviate from experiment in a homogeneous manner, that is, without serious outliers, compared to several other potentials. Spatial distribution functions (i.e., g OO (r,Ω)) and the (more common) radial distribution functions are used to analyze the local water structure. At the lone pair side of a central water, neighboring waters form a continuous horseshoe-like distribution, with substantial narrowing in the central part. The latter feature is unique to the QCT potential. Under high pressure, the local structure undergoes dramatic rearrangement and results in the collapse of second shell neighbors into the interstitial region of the first shell, which is in close agreement with experiment. Our results also corroborate the suggestion that the local hydrogen-bonded network remains largely intact even under such conditions.
Simulation of liquid water using a high-rank quantum topological electrostatic potential
International Journal of Quantum Chemistry, 2004
For the first time a potential based on high-rank atomic multipole moments computed according to quantum chemical topology (QCT) has been used in molecular dynamics simulations. Completing earlier work on the performance of this QCT potential on small gas-phase van der Waals complexes we now focus on the liquid structure of water. Other than the parameter L, which keeps track of the rank of the electrostatic interaction, the current QCT potential contains only two adjustable parameters of the Lennard-Jones type. A system of 216 water molecules was simulated including long-range interactions represented by a high-rank multipolar Ewald summation. High-order multipolar interactions (L ϭ 5) are essential to recover the typical features of a liquid-like structure. Liquid simulations at five different temperatures showed a maximum in the density and a temperature profile that agrees fairly well with experiment. The density of simulated water at 300 K and 1 atm is about 0.1% off the experimental value, while the calculated potential energy of the liquid is within 3% of the experimental result. The experimental value of the self-diffusion coefficient is underestimated by 35%. The value of C p is overestimated by 40% and the thermal expansion coefficient ␣ by 37%. The calculated correlation coefficients between the calculated QCT profile and the experimental profile of g OO (r), g OH (r), and g HH (r) are 0.976, 0.970, and 0.972, respectively.
Molecular Multipole Potential Energy Functions for Water
The Journal of Physical Chemistry B, 2016
Water is the most common liquid on this planet, with many unique properties that make it essential for life as we know it. These properties must arise from features in the charge distribution of a water molecule, so it is essential to capture these features in potential energy functions for water to reproduce its liquid state properties in computer simulations. Recently, models that utilize a multipole expansion located on a single site in the water molecule, or "molecular multipole models", have been shown to rival and even surpass site models with up to five sites in reproducing both the electrostatic potential around a molecule and a variety of liquid state properties in simulations. However, despite decades of work using multipoles, confusion still remains about how to truncate the multipole expansions efficiently and accurately. This is particularly important when using molecular multipole expansions to describe water molecules in the liquid state, where the short-range interactions must be accurate, because the higher order multipoles of a water molecule are large. Here, truncation schemes designed for a recent efficient algorithm for multipoles in molecular dynamics simulations are assessed for how well they reproduce results for a simple three-site model of water when the multipole moments and Lennard-Jones parameters of that model are used. In addition, the multipole analysis indicates that site models that do not account for out-of-plane electron density overestimate the stability of a non-hydrogen-bonded conformation, leading to serious consequences for the simulated liquid.
Polarizable Atomic Multipole Water Model for Molecular Mechanics Simulation
The Journal of Physical Chemistry B, 2003
A new classical empirical potential is proposed for water. The model uses a polarizable atomic multipole description of electrostatic interactions. Multipoles through the quadrupole are assigned to each atomic center based on a distributed multipole analysis (DMA) derived from large basis set molecular orbital calculations on the water monomer. Polarization is treated via self-consistent induced atomic dipoles. A modified version of Thole's interaction model is used to damp induction at short range. Repulsion-dispersion (vdW) effects are computed from a buffered 14-7 potential. In a departure from most current water potentials, we find that significant vdW parameters are necessary on hydrogen as well as oxygen. The new potential is fully flexible and has been tested versus a variety of experimental data and quantum calculations for small clusters, liquid water, and ice. Overall, excellent agreement with experimental and high level ab initio results is obtained for numerous properties, including cluster structures and energetics and bulk thermodynamic and structural measures. The parametrization scheme described here is easily extended to other molecular systems, and the resulting water potential should provide a useful explicit solvent model for organic solutes and biopolymer modeling.
A single-site multipole model for liquid water
The Journal of Chemical Physics, 2016
Accurate and efficient empirical potential energy models that describe the atomistic interactions between water molecules in the liquid phase are essential for computer simulations of many problems in physics, chemistry, and biology, especially when long length or time scales are important. However, while models with non-polarizable partial charges at four or five sites in a water molecule give remarkably good values for certain properties, deficiencies have been noted in other properties and increasing the number of sites decreases computational efficiency. An alternate approach is to utilize a multipole expansion of the electrostatic potential due to the molecular charge distribution, which is exact outside the charge distribution in the limits of infinite distances or infinite orders of multipoles while partial charges are a qualitative representation of electron density as point charges. Here, a single-site multipole model of water is presented, which is as fast computationally as three-site models but is also more accurate than four-and five-site models. The dipole, quadrupole, and octupole moments are from quantum mechanical-molecular mechanical calculations so that they account for the average polarization in the liquid phase, and represent both the in-plane and out-of-plane electrostatic potentials of a water molecule in the liquid phase. This model gives accurate thermodynamic, dynamic, and dielectric properties at 298 K and 1 atm, as well as good temperature and pressure dependence of these properties.
Polarizable Water Potential Derived from a Model Electron Density
Journal of Chemical Theory and Computation, 2021
A new empirical potential for efficient, large scale molecular dynamics simulation of water is presented. The HIPPO (Hydrogen-like Intermolecular Polarizable POtential) force field is based upon the model electron density of a hydrogen-like atom. This framework is used to derive and parametrize individual terms describing charge penetration damped permanent electrostatics, damped polarization, charge transfer, anisotropic Pauli repulsion, and damped dispersion interactions. Initial parameter values were fit to Symmetry Adapted Perturbation Theory (SAPT) energy components for ten water dimer configurations, as well as the radial and angular dependence of the canonical dimer. The SAPTbased parameters were then systematically refined to extend the treatment to water bulk phases. The final HIPPO water model provides a balanced representation of a wide variety of properties of gas phase clusters, liquid water, and ice polymorphs, across a range of temperatures and pressures. This water potential yields a rationalization of water structure, dynamics, and thermodynamics explicitly correlated with an ab initio energy decomposition, while providing a level of accuracy comparable or superior to previous polarizable atomic multipole force fields. The HIPPO water model serves as a cornerstone around which similarly detailed physicsbased models can be developed for additional molecular species.
Molecular Density Functional Theory of Water
The Journal of Physical Chemistry Letters, 2013
Three-dimensional implementations of liquid-state theories offer an efficient alternative to computer simulations for the atomic-level description of aqueous solutions in complex environments. In this context, we present a (classical) molecular density functional theory (MDFT) of water that is derived from first principles and is based on two classical density fields, a scalar one, the particle density, and a vectorial one, the multipolar polarization density. Its implementation requires as input the partial charge distribution of a water molecule and three measurable bulk properties, namely, the structure factor and the k-dependent longitudinal and transverse dielectric constants. It has to be complemented by a solute−solvent threebody term that reinforces tetrahedral order at short-range. The approach is shown to provide the correct 3-D microscopic solvation profile around various molecular solutes, possibly possessing H-bonding sites, at a computer cost two to three orders of magnitude lower than with explicit simulations.
A Molecular Density Functional Theory of Water
2016
Three dimensional implementations of liquid state theories offer an efficient alternative to computer simulations for the atomic-level description of aqueous solutions in complex environments. In this context, we present a (classical) molecular density functional theory (MDFT) of water that is derived from first principles and is based on two classical density fields, a scalar one, the particle density, and a vectorial one, the multipolar polarization density. Its implementa-tion requires as input the partial charge distribution of a water molecule and three measurable bulk properties, namely the structure factor and the k-dependent lon-gitudinal and transverse dielectric constants. It has to be complemented by a solute-solvent three-body term that reinforces tetrahedral order at short range. The approach is shown to provide the correct three-dimensional microscopic sol-vation profile around various molecular solutes, possibly possessing H-bonding sites, at a computer cost two-three...
United polarizable multipole water model for molecular mechanics simulation
The Journal of chemical physics, 2015
We report the development of a united AMOEBA (uAMOEBA) polarizable water model, which is computationally 3-5 times more efficient than the three-site AMOEBA03 model in molecular dynamics simulations while providing comparable accuracy for gas-phase and liquid properties. In this coarse-grained polarizable water model, both electrostatic (permanent and induced) and van der Waals representations have been reduced to a single site located at the oxygen atom. The permanent charge distribution is described via the molecular dipole and quadrupole moments and the many-body polarization via an isotropic molecular polarizability, all located at the oxygen center. Similarly, a single van der Waals interaction site is used for each water molecule. Hydrogen atoms are retained only for the purpose of defining local frames for the molecular multipole moments and intramolecular vibrational modes. The parameters have been derived based on a combination of ab initio quantum mechanical and experiment...
Molecular dynamics study of high-density liquid water using a modified central-force potential
Chemical Physics, 1984
Molecular dynamics simulations of liquid water at densities of 0.9718 and 1.346 g/cm3. and at temperatures of 63 and 77'T have been performed employing a modified version of the central-force model of water. The structural changes observed are in reasonably good agreement with recent high-pressure neutron scattering studies. The self-diffusion coefficient has been found to decrease by = 35% on compression. The OH stretching frequency underwent a shift of 10 cm-' in the direction of lower frequencies and was accompanied by an increase in the average O-H bond length. 37s G. Jan& et al. / MD sinzuiarion of high-density liquid water