How to apply shear force of a 3D block .can anyone provide Lammps input script on the application of shear force between two different fixed layer of a block?
Relateive keyword is deform in LAMMPS which can shear 3D block for your first question.
Shear force between two different fixed layer of a block can be realized by fix move keyword applied for the upper block. The five move keyword will force the upper block to move regardless of its force on it.
Or you can shear the upper block by ATOMSK or PYTHON code.