Re: [ESPResSo-users] (no subject)

[Farnoosh Farahpoor]

Dear Salvador

I am not an expert in ESPResSo but as Narges already mentioned, when you are able to write your potential and force as a closed form (as it is in your case), it seems to be more efficient to add the force field to the source files. We did it before and according to very clean implementation of ESPResSo it is an easy job.

In simplest case you can just use and change the external force defined in force.c.

Best,

Farnoush

On Fri, Nov 30, 2012 at 7:26 PM, Narges Nikoofard <address@hidden> wrote:

Dear Farnoosh,

Thanks! I hope you are also fine.

I hope your success in your project!

Bests,
Narges

On Fri, Nov 30, 2012 at 2:15 PM, Farnoosh Farahpoor <address@hidden> wrote:

Dear Narges

How are you?

Thanks for your kind reply. In fact in my new project I have an electric field which is impossible to write it in a closed form. I obtain it from a FEM solution. 

In our last study I had a field with a closed form and exactly as you said I changed the file "constraint.h". 

I think Stefan's solution is the best for me.

Thank you again.

Best regards,

Farnoush

On Fri, Nov 30, 2012 at 1:56 PM, Narges Nikoofard <address@hidden> wrote:

Dear Farnoosh,

I am not an expert in ESPResSo. But I have some time added an electric field varying in space to the ESPResSo. It you can write the force field in a closed form, it might be helpful. The changes should be made to the file "constraint.h". It would be very similar to the external magnetic field constraint, except that the particle position should also be in the inputs to the constraint function. Also, because a new constraint is defined, some minor changes are needed in the files "constraint.c" or "interaction_data.h".

If you think that this is useful, I can send you the changed files.

As some problems occured in my email, I hope that this email has not reached everyone twice!

Bests,
Narges

On Thu, Nov 29, 2012 at 5:28 PM, Farnoosh Farahpoor <address@hidden> wrote:

Dear all

I want to apply a force field with a complicate functionality in position. The force field depends on the position of the particle and is obtained from a finite element calculation.

Is there a way to apply such a force in integration process of ESPResSo? If not is there any idea about what is the best way to add it to the source files (in which file)?

Best regards,

Farnoush

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On Fri, Nov 30, 2012 at 7:03 PM, Salvador H-V <address@hidden> wrote:

Dear Stefan.

I am interested in study the dynamical properties of colloids on corrugated substrates.

In the simulation I need to apply a potential to mimic the corrugated surface. 

The potential is very simple (in my case) but then the force is position dependent:

V(x) = Vo * Sin(2 Pi x/lambda)

Vo => strength

lambda => Periodicity

Do you think that your implementation could do the trick to apply such potential and forces with ESPResSo?

Thanks a lot,

Salvador H-V