Re: [ESPResSo-users] Applying an External Field

[Narges Nikoofard]

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:
>    Dear All,
>    I want to simulate a two-dimensional colloidal system of particles
>    interacting through the Debye-HA 1/4ckel potential. But I am also
>    interested in applying an external field that mimics a substrate.
>    Each particle is subjected to A an external potential like this,
>    Uext(xi) = A strength of the external potential * A sin ( constant * x(i)
>    )
>    If I understood well, I can not use the ext_force command neither the
>    tabulated potential.
>    I would really appreciate any suggestions for the implementation.A
>    At this moment I have only a very simple idea of setting integrate to 1
>    and then apply the external force in x-direction in each step.A
>    However , I think this is highly inefficient and makes the simulation runs
>    slowly A
>    A
>    Thanks in advance.
>    Salvador H-V
>    A

constraint.c
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constraint.h
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constraint_tcl.c
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constraint_tcl.h
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