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The mechanism for the 3 x 3 distortion of Sn/ge (111)

S. de Gironcoli·S. Scandolo·G. Ballabio·G. Santoro·E. Tosatti
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Abstract

We show that two distinct $3 \times 3$ 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.

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S. de Gironcoli, S. Scandolo, G. Ballabio, G. Santoro, E. Tosatti. 1999-12-20. The mechanism for the 3 x 3 distortion of Sn/ge (111). https://doi.org/10.1016/s0039-6028(00)00066-2

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