SYMMETRY-BROKEN HF SOLUTIONS FOR GRAPHITE SURFACES

Closed-shell Hartree-Fock calculations on 2D-graphite monolayer, doubl e layer, and triple layer have been performed using the CRYSTAL92 prog ram package. Additional a posteriori density functional correlation co rrections were performed on the monolayer. In all cases the symmetry i mposed was a trigonal subgroup of the structural symmetry. Starting wi th different atomic populations resulted in either symmetrical or symm etry-broken electronic final states. The latter can be understood as r esults of the different stacking possibilities of the CDW and classica l solution of the 2D graphite monolayer. The results can consistently explain the trigonal STM pattern, not only of the surface of 3D graphi te but also of graphite monolayers on Pt(111), as well as the hexagona l patterns obtained with STM at large bias and with AFM.