How does it affect the diameter of the particle in the simulation?

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1

Dear ,

I am new to LAMMPS . What affects the diameter of the particles ?

Consider the following configuration:

2

Dear ,

I am new to LAMMPS . What affects the diameter of the particles ?

Consider the following configuration:

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Case atom_style atomic(point particle):

units lj
atom_style atomic
dimension 3

lattice sc 0.001
region box block 0 10 0 10 0 10
create_box 1 box
create_atoms 1 box

mass 1 1

velocity all create 1.44 87287 loop geom

pair_style lj/cut 2.5
pair_coeff 1 1 1.0 1.0 2.5

neighbor 0.3 bin
neigh_modify delay 5 every 1

fix 1 all nve

run 10

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and atom_style sphere withs diameters 100000:

units lj
atom_style sphere
dimension 3

lattice sc 0.001
region box block 0 10 0 10 0 10
create_box 1 box
create_atoms 1 box

set type 1 diameter 100000
set type 1 mass 1

velocity all create 1.44 87287 loop geom

pair_style lj/cut 2.5
pair_coeff 1 1 1.0 1.0 2.5

neighbor 0.3 bin
neigh_modify delay 5 every 1

fix 1 all nve

run 10
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In both cases the mass is 1.

Dump results and outputs are identical although in one case the particle
diameter is 100,000 times greater than the other .

they *have* to be identical, since the pair_style lj/cut as well as
the fix nve integrator treat all particles as point particles. the
_effect_ of the lennard-jones potential is that particles act as if
they have a certain "effective diameter", but that is represented by
the parameter sigma of the LJ potential (while epsilon describes the
strength of the interaction).

Even for both the box was filled with 1000 particles , although in the case
sphere volume all areas is much higher than the box itself .

doesn't matter.

Otherwise, use the option adiam dump_modify can modify the diameter as you
want to affect what I see in the simulation. Why you must manually place the
diameter in dump_modify and is not automatically resolved ?

again, dump image doesn't know anything about extended particles
(which is an optional property of atoms), but rather is based on
inferring the diameter used for visualization on other properties
associated with the atom type.

Help, I 'm confused . I do not understand what the effect of the finite
particle size for this type of simulation , maybe I need to add something
more .

you are not simulating finite size particles. the diameter property is
ignored throughout.

axel.