No abstract

We show that two distinct 3 × 3 ground states, one nonmagnetic, metallic, and distorted, the other magnetic, semimetallic (or insulating) and undistorted, compete in α-phase adsorbates on semiconductor (111) surfaces. In Sn/Ge(111), LSDA/GGA calculations indicate, in agreement with experiment, that the distorted metallic ground state prevails. The reason for stability of this state is analysed, and is traced to a sort of bond density wave, specifically a modulation of the antibonding state filling between the adatom and a Ge-Ge bond directly underneath.

No abstract