Reconstruction Mechanism and Surface-State Dispersion for Si(111)-(2×1)

Pseudopotential total-energy calculations show that the $\pi$-bonded chain reconstruction of the Si(111)-(2×1) surface can be reached from the ideally bonded surface without increasing the total energy by more than 0.03 eV/(surface atom). Hence, the chain surface can be formed easily in the cleavage process. The minimum-energy chain geometry is determined, and the corresponding surface-state dispersion is in remarkable agreement with recent angle-resolved photoemission experiments.