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

Best Wishes

Liyi Bai

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.

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

Sorry, but you are only repeating what you already wrote.

This is insufficient to give any good advice on how you propose to address your problem.

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

Axel

Dear Axel.

Sorry for my less experience to explain problem clearly.

Please give me one more chance to address my problem.

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. 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?

Thank you very much for your patience.

Liyi Bai

Dear Axel.

Sorry for my less experience to explain problem clearly.

Please give me one more chance to address my problem.

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.