科研之友
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摘要
Taking Cu as an example, the surface stress and surface energy in three low index surfaces and two families of representative surfaces (h k 0) and (h h l) belong to [0 0 1]- and [(1) over bar 1 0]-rotating axis respectively, have been calculated using MEAM. For the three low index surfaces, the decrease in the surface energy is small after relaxation, while the surface stresses in the surface planes tau(chi chi) and tau(gamma gamma) show opposite changes (decreasing and increasing) for inward and outward relaxations. The resulting relaxation direction is related to the normal stress tau(zz) before relaxation. For the surfaces of the (h k 0) and (h h l) families, with the increasing angle alpha (between the (h k 0) and (1 0 0) planes, and between (h h l) and (0 0 1) planes, respectively), the surface stress and surface energy go through an oscillatory change. The surface stress and surface energy are symmetric about the planes (1 0 0), (1 1 0) and (0 1 0) at alpha = 0 degrees, 45 degrees and 90 degrees, and about the planes (0 0 1) and (1 1 0) at alpha = 0 degrees and 90 degrees respectively, due to crystal symmetry.
