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Re: [lammps-users] dump to force

# Re: [lammps-users] dump to force

 From: Axel Kohlmeyer Date: Sun, 17 Dec 2017 23:56:27 -0500

On Sun, Dec 17, 2017 at 10:22 PM, liyi bai wrote:
Dear Axel.

Sorry for my less experience to explain problem clearly.

My main point is this: I want to compute the interactions between atoms .Three groups in my system A B C.I want to calculate inter-molecular force for each atom in group A considering the effects of group B and group C.

​you are *again​* simply repeating the same thing, and you are not very precise. neither do you explain how your system is set up specifically, not

So compute should perform the interactions between the atoms in group A and the atoms in group B,C.  I confused which compute style I need use, command "compute property/atom" or "compute stress/atom".If I use compute stress/atom,do I also need use compute reduce after that?

​how can compute stress/atom give you forces? have you actually *read* the documentation of what compute property/atom does? ​does any of those give any indication that they collect data for interactions between two or more groups?

Thank you very much for your patience.

​...and why have you not looked into what compute group/group does? it is very irritating to have people ask for advice and not pay *any* attention to what is​ suggested.

axel.

Liyi Bai

2017-12-18 12:01 GMT+09:00 Axel Kohlmeyer :
Sorry, but you are only repeating what you already wrote.

The obvious method to compute the interactions between groups is compute group/group.

Axel

--
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.

On Dec 17, 2017 21:53, "liyi bai" <liyibai2011@...24...> wrote:
Dear Axel,

Sorry for unclear information.
My point is, I want to calculate the LJ force on each atom in group A which effected by group B and C.How can I setup input to perform this force calculation correctly.

Thank you very much for your help.

Liyi Bai

2017-12-18 11:45 GMT+09:00 Axel Kohlmeyer :

On Sun, Dec 17, 2017 at 9:35 PM, liyi bai wrote:
Dear LAMMPS users,

I am trying to dump the atom attributes fx,fy,fz for each atoms in particular group.The problem like this: I have threes groups A.B and C.I want to calculate the atom attributes during the MD,only considering the inter-molecular interactions.Then output the fx,fy,fz for each atoms in group A( consider the effects of group B and C on group A). Firstly,I have used the "neigh_modify" to exclude the interactions in the same group.Can I reach my purpose by those command lines below?

group  A  type 1
group  B   type 2
group  C   type 3

compute   1  all stress/atom NULL
compute   2  all reduce sum c_1[1] c_1[2] c_1[3]

dump         3  all  custom 500 dump.force id type fx fy fz

​there is not enough information here to give a definite answer.

axel.​

Best Wishes

Liyi Bai

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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.