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Re: [lammps-users] Difference in results for atomstyle charge and dipole
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Re: [lammps-users] Difference in results for atomstyle charge and dipole


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Thu, 6 Jul 2017 16:18:01 -0400

On Thu, Jul 6, 2017 at 4:14 PM, John Smith <johnson21smith@...24...> wrote:
> In order to do this, I had to change the dimension to 3d and changed the
> lattice from sq to sc and boundary p p f. Since I cannot enforce2d in a 3d
> simulation, how do I zero out forces and velocities in z direction?

velocity command and then fix setforce?

axel.

>
>
>
> On 6 July 2017 at 13:29, Axel Kohlmeyer <akohlmey@...24...> wrote:
>>
>> On Thu, Jul 6, 2017 at 2:27 PM, John Smith <johnson21smith@...24...>
>> wrote:
>> > I looked into the documentation and updated the pair_style to
>> > lj/cut/dipole/long to account for dipole-dipole interactions. I also
>> > changed
>> > from 'fix nve' to 'fix nve/sphere update dipole'. The documentaion said
>> > that
>> > I need to include
>> >
>> > kspace_style ewald/disp 1e-4
>> >
>> > But I am getting an error that that command cannot be used in a 2D
>> > simulation. How do I effectively make this into a 3D simulation and get
>> > the
>> > same results? Or can is there a workaround to getting the above command
>> > working in 2d?
>>
>> please see kspace_modify slab.
>>
>> axel.
>>
>> >
>> > Thanks,
>> > John
>> >
>> > On 5 July 2017 at 18:05, Axel Kohlmeyer <akohlmey@...24...> wrote:
>> >>
>> >> On Wed, Jul 5, 2017 at 6:39 PM, John Smith <johnson21smith@...24...>
>> >> wrote:
>> >> > Hello,
>> >> >
>> >> > I am attaching two input scripts, one with a mixture SRD of style
>> >> > charge
>> >> > (initial charge set to 0.0) and the other with a net dipole of 1.0
>> >> > (in
>> >> > reduced lj units). I expected to see an effect due to electric field
>> >> > on
>> >> > the
>> >> > system in the case of dipole, but I am not able to observe any
>> >> > difference
>> >> > between the results of the two runs. I am also attaching the graphs
>> >> > for
>> >> > vacf, msd and diffusion coeffcient calculated using msd.
>> >> >
>> >> > I have used fix efield, but I am not sure if it is being called?
>> >>
>> >> as the fix efield documentation states, fix efield adds a torque to
>> >> particles with a (point) dipole.
>> >> however, there is nothing in your input, that is in any way reacting
>> >> to this torque (or to the dipole outside of fix efield).
>> >>
>> >> axel.
>> >>
>> >> > Any advice please?
>> >> >
>> >> > Sincerely,
>> >> > John
>> >> >
>> >> >
>> >> >
>> >> > ------------------------------------------------------------------------------
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>> >> > _______________________________________________
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>> >> > lammps-users@lists.sourceforge.net
>> >> > https://lists.sourceforge.net/lists/listinfo/lammps-users
>> >> >
>> >>
>> >>
>> >>
>> >> --
>> >> 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.
>
>



-- 
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.