shear modulus for thin film

Dear lammps users,

I am thinking about getting the shear modulus for very thin film ( 2 nm ), self assembled monolayer on si substrate, which is infinite in x and y direction. It is easy to get the shear modulus in xy direction by tilting the simulation box, What if I would like to get the shear modulus in xz direction? Can I also tilt the simulation box in xz? But the problem is that z direction is unperiodic.



You can't use fix deform in a non-periodic dimension.
It makes no logical sense as there is nothing
to shear if there is a free surface. You can always
grab the top level +z atoma and pull them to one
side and measure the response, but that is a different