[gmx-users] pressure coupling for lipid bilayer

[Xavier Periole]

Anton Feenstra wrote:

> Xavier Periole wrote:
> >
> > Using a surface tension is often necessary to reproduce the surface area
> > (per lipid) determine experimentally for most (if not all) of the known
> > lipid bilayers.
>
> Excuse me for maybe stating the obvious (am I missing the point?) but
> shouldn't the lipid forcefield parameters be optimized to reproduce
> the proper surface area per lipid? It seems terribly ad-hoc to me to
> correct a 'faulty' model in this way.
>

Yes, the lipid forcefield parameters should reproduce all the properties
of the membrane. But because, in the case of the surface area, the limitation

in size of the patch you can simulate introduces a systematic scrinckage
of your lateral box dimension (ref: SE Feller and RW Pastor, Biophysical J.,
1996 vol 71 p 1350), you have to apply a surface tension that rectify this.
The forcefield is not the problem, the size of the system is the problem.


Xavier