The interaction of hdyrogenated Si(001) surfaces is studied by means of molecular dynamics using an empirical potential. Above a certain critical external force covalent bonds may be formed between the surfaces even at room temperature, leaving a hydrogenated interface. The critical force is related to the assumptions of the molecular dynamics, thus scaling with the potential, heat transfer, boundary conditions, and the weak long-range interaction omitted. Below this critical force, the hydrogen–hydrogen interactions prevent covalent bonding. ©1997 American Institute of Physics.