title: Hydration of alkali ions from first principles molecular dynamics revisited.
abstract: Structural and dynamical properties of the hydration of Li(+), Na(+), and K(+) in liquid water at ambient conditions were studied by first principles molecular dynamics. Our simulations successfully captured the different hydration behavior shown by the three alkali ions as observed in experiments. The present analyses of the dependence of the self-diffusion coefficient and rotational correlation time of water on the ion concentration suggest that Li(+) (K(+)) is certainly categorized as a structure maker (breaker), whereas Na(+) acts as a weak structure breaker. An analysis of the relevant electronic structures, based on maximally localized Wannier functions, revealed that the dipole moment of H(2)O molecules in the first solvation shell of Na(+) and K(+) decreases by about 0.1 D compared to that in the bulk, due to a contraction of the oxygen lone pair orbital pointing toward the metal ion.
authors.affiliation: Synchrotron Radiation Research Unit, Quantum Beam Science Directorate (QuBS), Japan Atomic Energy Agency (JAEA), 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ikeda
authors.forename: Mauro
authors.initials: M
authors.lastname: Boero
authors.forename: Kiyoyuki
authors.initials: K
authors.lastname: Terakura
mesh_terms: D002627:Chemistry, Physical / Q000379:methods*; D003198:Computer Simulation; D004058:Diffusion; D004581:Electronics; D006878:Hydroxides / Q000737:chemistry; D007477:Ions; D008094:Lithium / Q000737:chemistry; D008962:Models, Theoretical; D008968:Molecular Conformation; D011188:Potassium / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D012984:Software; D013816:Thermodynamics; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D006878:Hydroxides; D007477:Ions; D014867:Water; D008094:Lithium; D012964:Sodium; D011188:Potassium