Re: [ESPResSo-users] Applying an External Field

[Kai Szuttor]

Hi again,

you can also have a look at the branch poiseuille_force on my github
fork of Espresso: https://github.com/KaiSzuttor/espresso/tree/poiseuille_force
Theres an implentation of a penetrable constraint
which interacts with particles depending on the distance.
Maybe thats what your looking for. All you have to do is to implement a
new interaction for your external field.

Cheers,

Kai Szuttor
On Wed, Dec 16, 2015 at 06:52:23AM -0600, Salvador H-V wrote:
>    Hi,
>    Thanks a lot for your answers.A 
>    I will take a look to the files and try to implement the external field.
>    Kind regards
>    Salvador
>    On Wed, Dec 16, 2015 at 5:33 AM, Narges Nikoofard <address@hidden>
>    wrote:
> 
>      Hi,
> 
>      One way is to add an external electric field to the constraints. This
>      can be done by following the way that the external magnetic field is
>      implemented in the source codes (search for ext_magn in the files).
> 
>      Then, one can make the external electric field to depend on the position
>      of the particle. This means that you need an extra input (particle
>      positions) to the functions.
> 
>      I have done this before for an external electric field which exists only
>      inside a nanopore. The main changed files for espresso-3.2.0 are
>      attached. You may need to change other source files as well to define an
>      extra constraint.
> 
>      I hope this can be useful.
>      Best regards,
>      Narges Nikoofard
>      On Tue, Dec 15, 2015 at 12:42 PM, Kai Szuttor <address@hidden>
>      wrote:
> 
>        Hi,
> 
>        what you could do is to use a tabulated interaction potential and use
>        penetrable wall constraints. Just an idea, maybe that helps.
> 
>        Cheers,
> 
>        Kai
>        On Wed, Dec 09, 2015 at 10:27:16AM -0600, Salvador H-V wrote:
>        >A  A  Dear All,
>        >A  A  I want to simulate a two-dimensional colloidal system of
>        particles
>        >A  A  interacting through the Debye-HA 1/4ckel potential. But I am
>        also
>        >A  A  interested in applying an external field that mimics a
>        substrate.
>        >A  A  Each particle is subjected to A an external potential like
>        this,
>        >A  A  Uext(xi) = A strength of the external potential * A sin (
>        constant * x(i)
>        >A  A  )
>        >A  A  If I understood well, I can not use the ext_force command
>        neither the
>        >A  A  tabulated potential.
>        >A  A  I would really appreciate any suggestions for the
>        implementation.A
>        >A  A  At this moment I have only a very simple idea of setting
>        integrate to 1
>        >A  A  and then apply the external force in x-direction in each step.A
>        >A  A  However , I think this is highly inefficient and makes the
>        simulation runs
>        >A  A  slowly A
>        >A  A  A
>        >A  A  Thanks in advance.
>        >A  A  Salvador H-V
>        >A  A  A
> 
>    --
>    =o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o
> 
>    Dr. Salvador Herrera-Velarde
>    Simulacion Computacional de Materia Condensada Blanda
>    Sub-Direccion de Investigacion y Posgrado
>    Instituto Tecnologico Superior de Xalapa (ITSX)
>    SecciA^3n 5A Reserva Territorial s/n,A 
>    Col. Santa BA!rbara,A 
>    CP 91096
>    Xalapa, Ver. Mexico
> 
>    =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
>    compatibilidad entre
>    diferentes distribuciones

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