How to suppress out-plane dilatation and distortion for a 2D deformation?

Hello all,
Wish you a very good morning. I am conducting a tensile deformation on a Graphene Sheet (2D). But at 300K, the atoms due to temperature induced vibration moving out of plane hurting the mechanism I am looking at. Any possible way to constrain that 3rd dimensional movement of the atoms and keep the sheet straight? Please kindly respond if you have any idea about this. Any help will be appreciated. Thanks a lot and have a great day.
Yours Truly
Anubhav Roy
Aerospace Engineering and Mechanics
University of Alabama
Tuscaloosa, US

Hello all,
Wish you a very good morning. I am conducting a tensile deformation on a
Graphene Sheet (2D). But at 300K, the atoms due to temperature induced
vibration moving out of plane hurting the mechanism I am looking at. Any
possible way to constrain that 3rd dimensional movement of the atoms and
keep the sheet straight? Please kindly respond if you have any idea about
this. Any help will be appreciated.

​there is always a way to suppress motion: set velocities to zero and keep
force zero.​ this can be done selectively for the x- y-, or z-component.
question is, however, is this a physical representation of the actual
behavior. while you can enforce this behavior in a computer, you cannot in
real life.