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Re: [lammps-users] Question about set up step potential in gcmc lammps
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Re: [lammps-users] Question about set up step potential in gcmc lammps


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Wed, 12 Jul 2017 23:45:20 -0400

On Wed, Jul 12, 2017 at 11:39 PM, vo thuy phuong Vo
<thuyphuongqnu@...24...> wrote:
> Hello Axel,
> Thank you for your help. As I read in the manual, I can set up region with
> different parameters (pressure, chemical potential). However, in this case,
> I want to keep these parameters same in two regions. In stead of set up
> different pressure or chemical potential, could I set up an external
> potential within a certain region that can help my lennard-jones particles
> confined in that region? Could I use the fix addforce command to do this? I
> plan to add an external force for particles if they move into particular
> region and without external force for other region. Is it possible?

this is different from what you asked before.
sure you can define an additional confinement potential.
fix addforce is one option, fix wall/region is another.

axel.

> Thank you very much!
>
> Best,
>
> Phuong
>
> 2017-07-10 21:08 GMT+10:00 Axel Kohlmeyer <akohlmey@...24...>:
>>
>> On Sun, Jul 9, 2017 at 11:47 PM, vo thuy phuong Vo
>> <thuyphuongqnu@...24...> wrote:
>> > Dear Lammps-users
>> > I am a new user Lammps and would like to perform gcmc using fix gcmc
>> > command
>> > in lammps. My system is a cylinder in which the middle region is put a
>> > deeper potential then outer region. As the definition of chemical
>> > potential
>> > in gcmc:
>> > mu=ln(particle density) + beta*potential.
>> > I would like to control mu constant by gcmc but the middle region has
>> > deeper
>> > potential so that the particles will be more in this region. I wonder
>> > can
>> > lammps support this feature which we can set up the different potential
>> > for
>> > different region (so that the obtained density particles will be
>> > different
>> > too) in gcmc (chemical potential is controlled to be constant)?
>> > As I look in the manual, we can set up different pressure but in this
>> > case,
>> > I would like to use the step potential for my system. Is it possible?
>> > Thank
>>
>> you can define two target regions (the inside and the outside of your
>> cylinder) and then set up two fix gcmc commands with different
>> parameters, each restricted to one of the two regions.
>>
>> axel.
>>
>> > you very much.
>> >
>> > Best,
>> >
>> > Phuong
>> >
>> >
>> >
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>> >
>>
>>
>>
>> --
>> Dr. Axel Kohlmeyer  akohlmey@...24...  http://goo.gl/1wk0
>> College of Science & Technology, Temple University, Philadelphia PA, USA
>> International Centre for Theoretical Physics, Trieste. Italy.
>
>



-- 
Dr. Axel Kohlmeyer  akohlmey@...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.