title: Flexible simple point-charge water model with improved liquid-state properties.
abstract: In order to introduce flexibility into the simple point-charge (SPC) water model, the impact of the intramolecular degrees of freedom on liquid properties was systematically studied in this work as a function of many possible parameter sets. It was found that the diffusion constant is extremely sensitive to the equilibrium bond length and that this effect is mainly due to the strength of intermolecular hydrogen bonds. The static dielectric constant was found to be very sensitive to the equilibrium bond angle via the distribution of intermolecular angles in the liquid: A larger bond angle will increase the angle formed by two molecular dipoles, which is particularly significant for the first solvation shell. This result is in agreement with the work of Hochtl et al. [J. Chem. Phys. 109, 4927 (1998)]. A new flexible simple point-charge water model was derived by optimizing bulk diffusion and dielectric constants to the experimental values via the equilibrium bond length and angle. Due to the large sensitivities, the parametrization only slightly perturbs the molecular geometry of the base SPC model. Extensive comparisons of thermodynamic, structural, and kinetic properties indicate that the new model is much improved over the standard SPC model and its overall performance is comparable to or even better than the extended SPC model.
authors.affiliation: Center for Biophysical Modeling and Simulation and Department of Chemistry, University of Utah, 315 South 1400 East Room 2020, Salt Lake City, Utah 84112-0850, USA.
authors.forename: Yujie
authors.initials: Y
authors.lastname: Wu
authors.forename: Harald L
authors.initials: HL
authors.lastname: Tepper
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Voth
mesh_terms: D000465:Algorithms; D002627:Chemistry, Physical / Q000379:methods*; D003198:Computer Simulation; D004058:Diffusion; D004563:Electrochemistry / Q000379:methods; D006859:Hydrogen / Q000737:chemistry; D006860:Hydrogen Bonding; D007700:Kinetics; D015233:Models, Statistical; D008962:Models, Theoretical; D008968:Molecular Conformation; D010100:Oxygen / Q000737:chemistry; D013816:Thermodynamics; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D006859:Hydrogen; D010100:Oxygen