Date: Fri, 15 Jun 2012 02:26:20 -0700
Hi Giovanni,
> is there any reference regarding the use of gamma_ten=17 as a reliable
> value
> for surface tension?
> Because for instance I found out this paper:
> http://onlinelibrary.wiley.com/doi/10.1002/jcc.20748/abstract
> where they say that for POPC parametrized with the .gaff force field
> work
> pretty well if surface tension is set to 60 mN/m.
> I guess however that it depends on the different parametrization
> performed
> by gaff.
We are in the process of trying to get a manuscript describing the Lipid 11
force field published. Unfortunately as you might imagine given the
competition in simulating lipids we are encountered a little bit of
animosity which is unfortunately delaying publication.
The value you quote is for using the GAFF force field. It is also highly
dependent on specifically which atom types were chosen, not everybody
chooses the same atom types consistently when using GAFF for lipids. They
also don't always calculate the charges in a consistent way. Thus the value
you need varies by implementation. For the current version of the Lipid 11
force field (released with AMBER 12) we have found a value of 17 tends to be
optimal for POPC. See the attached plot.
All the best
Ross
/\
\/
|\oss Walker
---------------------------------------------------------
| Assistant Research Professor |
| San Diego Supercomputer Center |
| Adjunct Assistant Professor |
| Dept. of Chemistry and Biochemistry |
| University of California San Diego |
| NVIDIA Fellow |
| http://www.rosswalker.co.uk | http://www.wmd-lab.org/ |
| Tel: +1 858 822 0854 | EMail:- ross.rosswalker.co.uk |
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(image/jpeg attachment: popc.jpg)
