[gmx-users] dissociative water models

[Erik Marklund]

26 jul 2007 kl. 07.55 skrev Mark Abraham:

> There's been some discussion lately on dissociative water models,  
> and I saw this paper http://dx.doi.org/10.1021/jp072530o, which may  
> be of interest to some people.
>
> Dissociative Water Potential for Molecular Dynamics Simulations
> T. S. Mahadevan and S. H. Garofalini*
> J. Phys. Chem. B; 2007; ASAP Web Release Date: 30-Jun-2007
>
> A new interatomic potential for dissociative water was developed  
> for use in molecular dynamics simulations. The simulations use a  
> multibody potential, with both pair and three-body terms, and the  
> Wolf summation method for the long-range Coulomb interactions. A  
> major feature in the potential is the change in the short-range O-H  
> repulsive interaction as a function of temperature and/or pressure  
> in order to reproduce the density-temperature curve between 273 K  
> and 373 at 1 atm, as well as high-pressure data at various  
> temperatures. Using only the change in this one parameter, the  
> simulations also reproduce room-temperature properties of water,  
> such as the structure, cohesive energy, diffusion constant, and  
> vibrational spectrum, as well as the liquid-vapor coexistence  
> curve. Although the water molecules could dissociate, no  
> dissociation is observed at room temperature. However, behavior of  
> the hydronium ion was studied by introduction of an extra H+ into a  
> cluster of water molecules. Both Eigen and Zundel configurations,  
> as well as more complex configurations, are observed in the  
> migration of the hydronium.

Yeah. I read it a few days ago. If I remember correctly, it is  
parameterized for 0.1fs timesteps and uses three-body terms. The  
former makes me think twice before using it for large systems such as  
protein simulations, and the latter makes it computationally  
expensive I presume. Futhermore, it uses T- and P dependent terms to  
adjust the potential, which just from the top of my head seems to  
limit its usefulness for heterogeneous systems. Still, it could be  
interesting for some applications.

/Erik

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_______________________________________________
Erik Marklund, PhD student
Laboratory of Molecular Biophysics,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,	75124 Uppsala, Sweden
phone:	+46 18 471 4537		fax: +46 18 511 755
erikm at xray.bmc.uu.se	http://xray.bmc.uu.se/molbiophys