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Abstract
We report a molecular dynamics simulation of liquid water using the SWM4NDP polarizable water model that belongs to the class of Drude oscillator type models. Generally, parameterisation protocols currently used for this type of models implicitly assume the validity of pointdipole approximation for the induced dipole (where the response of the dipole to the external field should depend only on the value of polarizability but not on the actual values of the charge or spring constant of the Drude oscillator). Therefore, possible dependency of the model results from the Drude charge/spring constant is often neglected. However, we show in this paper that the pointdipole approximation condition is actually not satisfied for a range of Drude oscillator parameters; that leads to a significant dependency of the obtained results from the particular choice of the Drude charge/spring constant. We analyzed the influence of the Drude charge value on the main macroscopic properties of water given by the SWM4NDP water model (including density, static dielectric constant, selfdiffusion constant, and surface tension). Our results show that (in general) the properties of model water do depend on the Drude charge value. We also provide an estimate for the Drude charge value ( 10e) above which the pointdipole limit is achieved with good accuracy. In this paper we also discuss the differences in the convergence behaviour of different model water properties. Based on the obtained results we developed a new reparameterised version of the SWM4NDP model (SWM4NDP10e) where the pointdipole limit condition is satisfied. We show that the model reproduces well important macroscopic as well as microscopic properties of water at ambient conditions.
Original language  English 

Pages (fromto)  245251 
Number of pages  7 
Journal  Journal of Molecular Liquids 
Volume  188 
DOIs  
Publication status  Published  1 Jan 2013 
Keywords
 pointdipole limit
 molecular dynamics
 water
 polarizable model
 drude charge value
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Projects
 1 Finished

E Infrastructure Bid  Capital Equipment Bid
Littlejohn, D., Fedorov, M., Mulheran, P. & Reese, J.
EPSRC (Engineering and Physical Sciences Research Council)
20/01/12 → 31/03/12
Project: Research