title: Instantaneous, parameter-free methods to define a solute's hydration shell.
abstract: A range of methods are presented to calculate a solute's hydration shell from computer simulations of dilute solutions of monatomic ions and noble gas atoms. The methods are designed to be parameter-free and instantaneous so as to make them more general, accurate, and consequently applicable to disordered systems. One method is a modified nearest-neighbor method, another considers solute-water Lennard-Jones overlap followed by hydrogen-bond rearrangement, while three methods compare various combinations of water-solute and water-water forces. The methods are tested on a series of monatomic ions and solutes and compared with the values from cutoffs in the radial distribution function, the nearest-neighbor distribution functions, and the strongest-acceptor hydrogen bond definition for anions. The Lennard-Jones overlap method and one of the force-comparison methods are found to give a hydration shell for cations which is in reasonable agreement with that using a cutoff in the radial distribution function. Further modifications would be required, though, to make them capture the neighboring water molecules of noble-gas solutes if these weakly interacting molecules are considered to constitute the hydration shell.
authors.affiliation: Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.
authors.forename: Anupam
authors.initials: A
authors.lastname: Chatterjee
authors.affiliation: Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Higham
authors.affiliation: Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Henchman
mesh_terms: D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D005741:Noble Gases / Q000737:chemistry*; D014867:Water / Q000032:analysis* / Q000737:chemistry*
chemical_list: D005741:Noble Gases; D014867:Water