Combined ab initio total energy density functional calculations and scanning tunneling microscopy experiments of the β-SiC(001)c(4x2) surface

First-principle total energy density functional calculations using a cluster approach demonstrate that the recently STM-imaged c(4x2) reconstruction of the fully Si-terminated beta-SiC(001) surface originates from symmetric Si dimers having not only alternating heights but also alternating bond lengths. The Si-terminated beta-SiC(001) surface is thus structurally totally different from the Si(001) c(4x2) reconstruction. These theoretical predictions bring new insights into the recent alternately up-and down-dimer model (AUDD model) proposed on the ground of STM measurements on beta-SiC c(4x2) surface.