atom_style full sphere

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1

Hi lammps users,

I have system with atom_style full sphere

I have a question reg. the integration part.

Can we define separate group for sphere (finite size) and full (point) particles as shown below ?

fix 1 sphere nve/sphere

fix 2 point nvt temp iso 0.0 0.0 100.0

Is this a correct way of approach.

Thanks

Spandana

2

yes, you can do that. You will need atom_style hybrid full sphere
if you need attributes beyond what sphere provides
for your point particles.

Steve

3

Thanks Steve,

I am integrating as mentioned above… I defined linear and angular velocities in data file… But angular velocities are not being changed. They are constant through out the simulation.
Thanks
Spandana

4

Thanks Steve,

I am integrating as mentioned above… I defined linear and angular velocities in data file… But angular velocities are not being changed. They are constant through out the simulation.

Well do they experience any kind of torque? Newton’s laws of motion apply to extended particles just as well.

Axel

5

Thanks axel for the reply. I want to apply torque for sphere atom style.
I am not sure whether abt the torque. How do we know that.

Thanks
Spandana

6

Thanks axel for the reply. I want to apply torque for sphere atom style.
I am not sure whether abt the torque. How do we know that.

It has to be part of your model. Most styles in lammps only treat point particles and thus generate no torque.

7

Thanks again,

I am sorry for the same repetitive question.
My atom style is full and sphere. I have given initial angular velocities to sphere atoms.
Integrated with nvr/sphere with update torque, but I am not seeing the updating of angular velocities.

I lost completely and need help. Should I need to do anything more.

Thanks
Karteek

8

Thanks again,

I am sorry for the same repetitive question.

if you keep asking the same question, chances are, you get the same
answer. not a very smart move, if you would ask me.

My atom style is full and sphere. I have given initial angular velocities to
sphere atoms.
Integrated with nvr/sphere with update torque, but I am not seeing the
updating of angular velocities.

fix nve/sphere will need torque as *input*. obviously you are not
using any style that *computes* the torque, thus it will be zero and
consequently angular velocities will not change. makes perfect sense,
but i have to guess since you provide insufficient details.

I lost completely and need help. Should I need to do anything more.

yes, you need to learn some classical mechanics. i can't help you there.

axel.

9

And if you initialized the angular velocities
to the target temperature, then the thermostat
nvt/sphere has nothing to do. It will leave
the angular velocities unchanged.

Steve