Periodic boundary condiion

LAMMPS LAMMPS General Discussion
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1

Dear LAMMPS experts,

When periodic boundaries are applied, how should the length in that dimension be interpreted? Is it considered infinite, or is there a specific way to calculate its effective length?

To provide context, I am working on calculating the moment of inertia for a 3D cantilever with dimensions L, h, and w along the x, y, and z axes, respectively. In this case, I have applied periodic boundary conditions along the z-axis.

Your insights would be greatly appreciated!

Best regards,
Bahman

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You need to work out yourself how the PBC affects the physics of your cantilever. Think about applying forces in these two cases:

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In case a) the cantilever will act as an infinite rod, assuming that the force applied is much smaller than the internal forces.
In case b) the cantilever will respond as a rigid object of length L=zhi-zlo.

In both cases, the forces are also applied to the periodic images. This should be clear if you know how PBCs work.