Re: [ESPResSo] orientational order parameter

[Olaf Lenz]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi!

Markus Deserno wrote:
> A negative order parameter only occurs for "anti-alignment",
> i.e., if lipids preferentially point AWAY from some given axis.
> Say, there is a north-south-axis, but all lipids point
> towards the equator.  Since this is a somewhat curious state
> to achieve, I indeed do not understand how it shows up in
> Martina's simulations.

OOps, Markus is of course right. I haven't used S for a while: S=-0.5
means that all lipids are pointing to the equator.

Still, the explanation might shed light onto Martina's problem. If I
look at the image that she has sent, it looks to me as though she is
using an elliptical (or even cylindrical?) vesicle. If out of some
reason, the director of the oop points along the long axis, this would
explain a value of close to -0.5.
Is it possible that you have to give the membrane normal (=director)
when computing the oop? If that is the case, what value did you choose?
If not: what is the director of the lipids?

Best regards

        Olaf

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.4-svn0 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

iD8DBQFKVFCstQ3riQ3oo/oRAs7PAJ4oMGV5NMOmg+4YCOcqtjOUsNs+mgCfVXNq
MZl352TymBLBjFmzBlOHN/E=
=LjTJ
-----END PGP SIGNATURE-----