On the importance of sp-electrons in the surface relaxation of d-band metals

We present arguments to the effect that the self-consistent smoothing of the mobile sp-electron distribution gives rise to electrostatic forces which are a major contribution to the initial relaxing forces on the outermost ions at a d-band metal surface. Numerical estimates for the (001) face of α-Fe are given, showing that for the surface ions the surface Madelung force from the sp-electrons is inward and about $\text{3}\text{1}\text{2}$ times stronger than an outward short-range force simulating the effect of d-electrons.