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## Re: [ESPResSo-users] Computing the structure factor

 From: Peter Kosovan Subject: Re: [ESPResSo-users] Computing the structure factor Date: Sat, 10 Mar 2012 23:31:11 +0100 User-agent: SquirrelMail/1.4.22

```Hello Salvador

What you get is always the structure factor of the instantaneous
configuration. The implementation of "analyze structurefactor" does not
contain an option to average over stored configurations. You need to
perform the averaging at the script level, or by an external tool.

If you are using Espresso 3.1, you may use the core observable
structurefactor in combination with the correlator to compute the average.

Cheers,

peter

--
Peter Kosovan
Institute of Computational Physics
University of Stuttgart
Pfaffenwaldring 27
70569 Stuttgart
Germany

On Fri, March 9, 2012 9:45 pm, Salvador H-V wrote:
> Hi everybody,
>
> I am simulating a system of particles in 3D interacting with WCA
> potential.
>
> During the sampling I am storing the configurations via the analyze append
> command.
>
> I want to calculate the radial distribution function and the structure
> factor of the suspension.
>
> To compute the structure factor I am using the following steps after
> (outside) sampling cyle
>
> set sq_file [open "\$outputdir/WCA-\$temp_ave.sq" "w"]
> puts \$sq_file "#q \t sq"
>
> set sq [analyze structurefactor 0 24 ]
> foreach val \$sq {
>    foreach {q s} \$val {}
>    puts \$sq_file "\$q \t \$s"
> }
> close \$sq_file
>
> I was wondering if am obtaining the average structure factor coming from
> all stored configurations or just the structure factor of one
> configuration.
>
> Any comment or suggestion would be greatly appreciated.
>
> Thanks a lot in advance,
>
>
> --
> =o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o
>
> Division de Ciencias e Ingenierias
> Campus Leon
>
> =o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o
>
> Este correo ha sido editado para evitar el uso de acentos y guardar