Surface stresses on symmetric (2 × 1) reconstructed Si(001) calculated from surface energy variations

On Si(001) vicinals, the orientation of the dimers on the (2 × 1) reconstructed terrace is mutually perpendicular on either side of a monoatomic step. Understanding the surface stresses on (2 × 1) reconstructed Si(001) is crucial for the discussion of forces representing steps and possibly stability issues at vicinal surfaces. The surface stresses are calculated from the surface energy variations in function of the deformation parallel to the surface. For the deformation parallel to the dimer rows (x), the first monolayer stress is high as for unreconstructed surfaces. For the other direction (y) parallel to the dimer axis, the first monolayer is weakly stressed while the second monolayer stress is high due to the bond between dimer atoms. In the direction diagonal between x and y, the first monolayer stress is decreased at the expense of the other surface monolayers. The surface stresses are calculated by using the MEAM potential. This potential considers the second nearest neighbouring (2NN) bond between dimer atoms while the 2NN bonds are screened in bulk. This paper validates clearly the Shuttleworth formula.