Abstract: Scanning tunneling microscope (STM) images and surface relaxations of a reconstructed W(100) c(2×2) surface have been investigated by density functional theory calculations. The distorted displacement (δ) of a tungsten atom along [110] was 0.027 nm. The distortion energy was 80.6 meV·atom-1 and the relaxations of the W(100) c(2×2) surface was calculated to be -7.6% for ⊿d12/d0 and +0.8% for ⊿d23/d0. The surface work function (Φ) was 4.55 eV. Calculated STMimages of the W(100) c(2×2) surface displayed the following unusual features: protrusions in the STM image along the [110] axis are in the middle of a zig-zag chain of tungsten atoms while the dark regions in STM images correspond to valleys between neighboring zig-zag chains. These are due to surface reconstruction. Typical corrugations of a STMscan have been calculated to be between 0.008-0.013 nm for negative bias voltages while the corrugation varies from0.019-0.024 nmfor positive bias voltages.

Key words: W(100) c(2×2) surface, Zig-zag distortion, STM image