Re: [ESPResSo] PSAW

[Mikheil Azatov]

Hi!

Yes I was talking about he polymer command.  The differences probably appear only in the equilibration part. I mean in the beginning of the simulation I had the maximum distances between particles in the polymer larger then when using SAW. The User Guide says just that statistics for PSAW is different then a statistics for SAW but it doesn't say in what way are they different. 

I also wanted to ask if constraints are walking for RW polymers. I usually create polymers with constraint command because i want them to be in a certain volume. After I create polymers I delete constraints. When I use PSAW and SAW commands for polymers everything works fine and the polymers are being created within that volume. For RW it doesn't work that way. The polymers are kind of "reflected" from the borders of constraints and can have other ends on the other side of the simulation box. I think sometime they even "merge" with each other( particles with different ID's that belong to different polymers are actually same particles). I don't use PBC and the output to vmd are unfolded coordinates, so i don't think it's connected to it. So i was wondering if constraints are actually working with RW and I'm just doing something wrong or they just don't work with RW polymers? 

Thanks,

Mikheil Azatov

2010/10/26 Olaf Lenz <address@hidden>

Hi!

On 10/25/2010 05:43 PM, Mikheil Azatov wrote:
> I wanted to ask question about PSAW. I switched from SAW to PSAW because
> SAW was taking way to much time. The particles are added much faster
> with PSAW but after I start the simulation i get weird results... So i
> was wondering if anyone knows how does PSAW work or can tell me where to
> read about it?

I assume that you refer to the polymer command? You can read about how
the algorithms work in the User's Guide.

What exactly do you mean by "weird results"? It is true that the chain
generated with the PSAW algorithm does not really match the SAW
statistics initially. However, if you do a simulation of the chain,
these differences should disappear when the system is equilibrated.

Olaf

--
Dr. rer. nat. Olaf Lenz
Institut für Computerphysik, Pfaffenwaldring 27, D-70569 Stuttgart
Phone: +49-711-685-63607