STRUCTURE OF MONATOMIC STEPS ON THE SI(001) SURFACE

The atomic and electronic structure of the stepped Si(001) surface is investigated by ab initio molecular dynamics. All configurations consi dered by us are unstable with respect to the buckling of the surface d imers. The ground state reconstruction depends on the type of the step and, in some cases, is different from that of the flat surface. The o bserved differences between the filled-state and the empty-state scann ing tunneling microscopy images are due to differences in wave functio n shapes rather than tip-induced reconstruction.