Adsorption of a carbon atom on the dimerized diamond (100) surface

Using tight-binding molecular dynamics, we study the structure of the dimerized C(100) surface and the adsorption of a carbon atom on that surface. The dimer is symmetric with a length of 1.40 Angstrom, in excellent agreement with the values obtained from previous Qb initio calculations. Adsorption and diffusion of a carbon adatom on the surface are very different from those of a silicon adatom on the dimerized Si(100) surface, mainly due to the stronger interaction between carbon atoms and the stronger directional nature of the bonds between carbon atoms: (i) the number of adsorption sites is two per (2 x 1) surface unit cell, located near each of the dimer atoms, and (ii) diffusion barriers are higher and almost isotropic.