Simple comments on the W(001) surface instability

A model of step geometry on the reconstructed W?(001) surface

“…The "ideal" MS structure is restored starting from the 4th atomic chain. The well resolved differences are fround, however, at the edge for the (it) step and in two first rows in the (10) case. For the (11) terrace, it is possible to impose two different boundary conditions ~vith improper MS polarization on the 14th row.…”

“…The results arrived at for the (10) and (11) step are presented in figure I. We describe explicitly only those displacements, magnitudes and angles of which differ from the MS values more than about 0.02 A and 2°, respectively.…”

“…Naturally, legitimacy of equation (I) and the use of surface force constant values at the step edge can be questioned. However, investigations [8][9][10] suggest that the very nature of interactions is common for many atomic arrangements (including steps) on W (Ml) and the repulsion originates flom indirect (mediated by the metal) interactions. Hence, the equation (I) with the repulsive linear term should be correct qualitatively at least.…”

“…Let us now explain the model of W(001) steps used below. The upper (Ml) terrace is modelled by a half-plane (or rather strip with a boundary condition) of atoms with the edge parallel to (10) and (11) direction, respectively. The Hamiltonian is exactly that of reference ii ii At edge atoms, however, the term Fl; is added, where I;is the deformation perpendicular to the edge and F is the force derived from the linear term in equation (I).…”

“…On the 14th (and following) row, the boundary condition assuming the ifs reconstruction with the amplitude 0.27 A ii ii b imposed. The period of the MS phase is two along the (10) rows and the same is supposed for the (10) step. For (it) chains, the MS period is one.…”