  Using Monte Carlo simulations within the empirical potential approach, we
examine the effect produced by the surface environment on the atomic level
stresses in tetrahedral amorphous carbon. Both the distribution of stresses and
the distributions of sp^2 and sp^3 atoms as a function of depth from the
surface are highly inhomogeneous. They show the same close relationship between
local stress and bonding hybridization found previously in the bulk of the
material. Compressive local stress favors the formation of sp^3 sites, while
tensile stress favors the formation of sp^2 sites.
