The plane-wave pseudopotential density functional theory ͑DFT͒ package FHI98MD has been used to optimize the geometry of the Si(111)ͱ3ϫͱ3R30°-B(S 5 ) configuration. The resultant geometry has been found to be in excellent agreement with recent experimental results. By calculating the band structure for the B(S 5 ) configuration and carefully analyzing the nature of the wave functions in the vicinity of the Fermi energy, we have been able to identify the surface states along the various symmetry

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... directions of the surface Brillouin zone ͑SBZ͒. The overall dispersion of both the occupied and unoccupied surface state bands is found to be in excellent agreement with the angle-resolved photoemission data. The theoretical calculations also predict the occurrence of two occupied surface state bands at the ⌫ and M points of the SBZ. The splitting of these bands is predicted to be 0.27 eV and 0.35 eV, respectively, in good agreement with experiment.