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Project T1: Ground- and excited-state properties of substrate-supported nanowires calculated from first principles

Simone Sanna, Wolf Gero Schmidt, Friedhelm Bechstedt

The proposed subproject aims at exploring in microscopic detail the intertwinement of
structural, vibrational, electronic, and magnetic properties of prototypical metal-induced
atomic-scale nanowires formed on semiconductor substrates. In particular it shall be
investigated how the anchoring of such a one-dimensional (1D) electronic system on the
spatially extended substrate – actually the precondition of its existence – manifests itself in
the spectral fingerprints and phase transitions of the atomic-scale wires. Thereby we focus
on the one hand on systems like In-Si(111), Au-Ge(001) or vicinal Au-Si(111) surfaces,
where Peierls-like transitions and Tomonaga-Luttinger liquid properties, respectively, have
been experimentally already demonstrated. These prototypical and well-established model
systems will be used to study in detail the influence of the environment and external
perturbations (e.g. chemical and optical doping) on the phase transition and its dynamics.
In addition, experimentally less well characterized systems such as silicide nanowires or
lead and noble/transition metal wires on vicinal substrates will be studied. These systems are interesting since they provide the wire separation and wire perimeter as additional tuning parameters that allow for studying the influence of the wire-wire coupling and wire geometry. Our subproject provides atomic geometries, vibrational frequencies and eigenmodes as well as electronic structure information (e.g. spin-resolved band structures) and spectroscopic fingerprints (e.g. IR and Vis/UV spectra) that help in the interpretation of the measurements in the experimental subprojects.



(Picture: Schematic drawing of the main structural motifs of the atomic-scale In wires formed on the Si(111) surface, In hexagons and zigzag chains, respectively.)