DIAMOND (111) AND (100) SURFACE RECONSTRUCTIONS

Fully converged ab initio density functional theory local density appr oximation (DFT-LDA) calculations are presented for C(111) and C(100) s urfaces using soft carbon pseudopotentials and plane waves with a cuto ff energy of 42 Ry. For the single and triple dangling bond surfaces, we study 2 X 1 and (root 3X root 3)R30 degrees reconstructions with re spect to their total energies, geometries and band structures. In cont rast with an earlier ab initio study, we find that the pi-bonded chain s are not dimerized in the 2X1 Pandey reconstruction. Chain and trimer reconstructions of the triple dangling bond face result in a consider able lowering of the total energy, The ground state of the (100) face is governed by symmetric dimers resulting in a 2X1 reconstruction.