Failure of potassium dimer formation on the β-SiC(100)-c (4 × 2) surface

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Using ab initio molecular dynamics, we study the formation of dimers on the β-SiC(100)-c(4 × 2) surface. According to previously published experimental results of Derycke et al. [Appl. Phys. Lett. 88(2), 022105 (2006)] (using scanning tunneling spectroscopy, core-level photoemission spectroscopy, and low-energy electron diffraction) the (100)-c(4 × 2) surface is highly prone to form potassium dimers. In their work, potassium atoms fill adjacent well-defined pedestal sites when there are lower coverages of potassium deposited onto the surface (∼0.16 monolayers). Contrary to the work by Derycke et al., we find that potassium does not prefer to form dimers on the (100)-c(4 × 2) surface, but rather potassium tends to reconstruct (after annealing simulations) by choosing distant pedestal sites in order to minimize the overlap of the ionic radii of the potassium atoms.