  The metallic character of the GeBi2Te4 single crystals is probed using a
combination of structural and physical properties measurements, together with
density functional theory (DFT) calculations. The structural study shows
distorted Ge coordination polyhedra, mainly of the Ge octahedra. This has a
major impact on the band structure, resulting in bulk metallic behavior of
GeBi2Te4, as indicated by DFT calculations. Such calculations place GeBi2Te4 in
a class of a few known non-trivial topological metals, and explains why an
observed Dirac point lies below the Fermi energy at about -0.12eV. A
topological picture of GeBi2Te4 is confirmed by the observation of surface
state modulations by scanning tunneling microscopy (STM).
