[lammps-users] Question regarding shear

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1

Dear Lammps users,

I have a small query regarding shear module of fix/deform command. Please see the attached figure.

Lets say we are shearing along X direction. How does fix/deform treat the interactions which are between the top and bottom atoms (along Y direction). According to my picture, there will be lot of strain --due to periodic boundary conditions-- on the highlight pair of atoms as top atom is getting sheared close to maximum while bottom is getting sheared a close to minimum. How does fix/deform treat this artificial strain. My picture might be wrong with respect to what fix/deform does. Any comments are highly appreciated.

Best Regards,
Vikas

shear.JPG

2

Your pic on the right is wrong. The top tilted box needs
to be shifted to the right, so that it lines up with the lower tilted
box. When ghost atoms are created for a tilted (triclinic)
box, that shift factor is applied to coords of the ghost atoms, so
the interactions don't see the boundaries, just as if
there were no tilt.

Steve

3

Dear Steve,
Thanks for the answer. I was getting that feeling but wasn’t sure.

Regards,
Vikas