Fully converged ab initio density functional theory local density approximation (DFT-LDA) calculations are presented for C(111) and C(100) surfaces using soft carbon pseudopotentials and plane waves with a cutoff 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 respect to their total energies, geometries and band structures. In contrast with an earlier ab initio study, we find that the pi-bonded chains are not dimerized in the 2X1 Pandey reconstruction. Chain and trimer reconstructions of the triple dangling bond face result in a considerable lowering of the total energy, The ground state of the (100) face is governed by symmetric dimers resulting in a 2X1 reconstruction.