[lammps-users] Neighbor_modify Exclude

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#1

Hi all

I want two types (I,J) of atoms not to interact with each other. So i am using pair_style lj/cut with pair_coeff I J 1.0 1.0 0.0 along with neighbor exclude type I J. But, I still see the effect of these interactions. Can anybody comment?

Thanks

Regards
Sreekanth

#2

Hi Sreekanth,

I’ve got the same issue but a bit different scenario – I need to do a simulation to one particle or to many that don’t have interaction between one another (like realizing the particles one after the other or from a change in position or forces).

Anyway, in the output I can’t find a way to control the number of particles or their interactions.

From documentation (1)–

“the number of atoms allowed can be increased by decreasing the maximum number of neighbors. For example placing,

neigh_modify one 100

in the input script will decrease the maximum number of neighbors per atom to 100, allowing more atoms to be run on the GPU.

”

So I tried using - neigh_modify one 0

Or using- neigh_modify one 1

Nothing makes the different.

I don’t know where I’m wrong…

(1) - lammps-25Oct09/doc/Section_start.html#2_7

Best regards,

Igal Krigel

#3

Show the input script and the fact that you are seeing the effect of these interactions. Then possibly someone could help.

#4

Hi all

I want two types (I,J) of atoms not to interact with each other. So i am
using pair_style lj/cut with pair_coeff I J 1.0 1.0 0.0 along with neighbor
exclude type I J. But, I still see the effect of these interactions. Can
anybody comment?

how do you assess that you see those interactions?

if you exclude pairs from the neighbor list that should be sufficient.
otherwise, i'd rather rely on setting epsilon to zero than the cutoff.

also, in dense systems, you can also see "fake" forces from
removing partial interactions to a particle asymmetrically.

cheers,
    axel.

#5

If you don't want particles to interact, then don't define a pair style.