Anomalous corrugations in scanning tunneling microscopy: Imaging of individual states

Unusual corrugations observed in scanning-tunneling-microscope (STM) images of 1T-TaS2, Si(111)(2×1), and graphite are explained, and are shown to be characteristic of materials where the Fermi surface has collapsed to a point at the corner of the surface Brillouin zone. This is the first clear case where the low-bias STM image is dominated by electronic structure effects rather than surface geometry. Implications for STM spatial resolution are discussed. © 1986 The American Physical Society.