STRUCTURE OF DIAMOND(100) STEPPED SURFACES FROM AB-INITIO CALCULATIONS

We present theoretical Studies of relaxations of monoatomic S-A, S-B(b ) and S-B(n) steps on the diamond(100)-(2x1) surface employing an nb i nitio molecular dynamics simulation method that is based on density fu nctional theory. Stable dimer structures are found in the upper and lo wer planes of the step surfaces in agreement with experiment. Signific ant atomic relaxations occur near the step edges of S-B(b) and S-B(n) stepped surfaces induced by the creation of the steps. Atomic H adsorp tion on these step surfaces to form monohydride structures is energeti cally favourable. We also simulate the presence of radical sites near the step edges of S-A, S-B(n) and S-B(b) and local reconstruction invo lving the dimer containing the radical sites is found. Electronic char ge density profiles of the filled states near the Fermi level show fea tures associated with the dimer structures.