Query about Torque calculation

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1

Dear Users,
    I have a query about torque calculation in LAMMPS. For example, if I
am taking a spherical shell made of smaller spheres and I use the 'fix
rigid' command to make the entire structure rigid. I have some other
particles in the system and the interactions between these spherical
shell and particles are set to be Lennard-Jones.I know that
Lennard-Jones is a central force, So what will be the torque on
spherical shell? How the torque is calculating in 'fix rigid' ?
As per my knowledge for symmetric particles like sphere the torque due to
LJ will be zero. Because torque (rxF) is the cross product of position
vector and force and here force is Lennard-Jones, which is a central
force.

Thanks in Advance

2

Dear Users,
    I have a query about torque calculation in LAMMPS. For example, if I
am taking a spherical shell made of smaller spheres and I use the 'fix
rigid' command to make the entire structure rigid. I have some other
particles in the system and the interactions between these spherical
shell and particles are set to be Lennard-Jones.I know that
Lennard-Jones is a central force, So what will be the torque on
spherical shell? How the torque is calculating in 'fix rigid' ?

please have a look at the source code if you want to know these kind of details.

As per my knowledge for symmetric particles like sphere the torque due to
LJ will be zero. Because torque (rxF) is the cross product of position
vector and force and here force is Lennard-Jones, which is a central
force.

why ask and having to trust some random person when you can easily set
up some experiments with LAMMPS and know for certain?

axel.

3

Also the fix rigid command can output the torque on each body
it defines. Compute rigid/local can do the same thing
when used with fix rigid/small.

Steve