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.
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