Molecular theories and simulation of ions and polar molecules in water

Abstract

Recent developments in molecular theories and simulation of ions and polar molecules in water are reviewed. The hydration of imidazole and imidazolium solutes is used to exemplify the theoretical issues. The treatment of long-ranged electrostatic interactions in simulations is discussed extensively. It is argued that the Ewald approach is an easy way to get correct hydration free energies in the thermodynamic limit from molecular calculations; and that molecular simulations with Ewald interactions and periodic boundary conditions can also be more efficient than many common alternatives. The Ewald treatment permits a conclusive extrapolation to infinite system size. The picture that emerges from testing of simple models is that the most prominent failings of the simplest theories are associated with solvent proton conformations that lead to non-gaussian fluctuations of electrostatic potentials. Thus, the most favorable cases for the second-order perturbation theories are monoatomic positive ions. For polar and anionic solutes, continuum or gaussian theories are less accurate. The appreciation of the specific deficiencies of those simple models have led to new concepts, multistate gaussian and quasi-chemical theories, that address the cases for which the simpler theories fail. It is argued that, relative to direct dielectric continuum treatments, the quasi-chemical theories provide a better theoretical organization for the computational study of the electronic structure of solution species.

invited J. Phys. Chem. feature article, 30 pages including 10 figures, minor stylistic revisions

References in corpus (4)

• Hydrolysis of ferric ion in water and conformational equilibrium
• Ion Sizes and Finite-Size Corrections for Ionic-Solvation Free Energies
• Quasi-chemical Theories of Associated Liquids
• Pressure Calculation in Polar and Charged Systems using Ewald Summation: Results for the Extended Simple Point Charge Model of Water

Cited by in corpus (20)

• Absolute Hydration Free Energies of Ions, Ion-Water Clusters, and Quasi-chemical Theory
• Ab initio molecular dynamics calculations of ion hydration free energies
• Real single ion solvation free energies with quantum mechanical simulation
• Interatomic potentials: Achievements and challenges
• The hydration state of HO${}^{-}$(aq)
• Electrostatic solvation free energies of charged hard spheres using molecular dynamics with density functional theory interactions
• Theory and simulations of rigid polyelectrolytes
• The optimal P3M algorithm for computing electrostatic energies in periodic systems
• Energies of ions in water and nanopores within Density Functional Theory
• Electrostatic fluctuations in cavities within polar liquids and thermodynamics of polar solvation
• Interfacial ion solvation: Obtaining the thermodynamic limit from molecular simulations
• Ion-water clusters, bulk medium effects, and ion hydration
• Assessing long-range contributions to the charge asymmetry of ion adsorption at the air-water interface
• Water coordination structures and the excess free energy of the liquid
• Solvated dissipative electro-elastic network model of hydrated proteins
• The Influence of Distant Boundaries on the Solvation of Charged Particles
• Quadrupole-mediated dielectric response and the charge-asymmetric solvation of ions in water
• Depolarized light scattering and dielectric response of a peptide dissolved in water
• Hydrodynamic Interactions in Ion Transport -- Theory and Simulation
• Ohta-Kawasaki energy for amphiphiles: asymptotics and phase-field simulations