Atomic structure of the Sb-induced Si(111)-(5 root 3x5 root 3)R30 degrees surface: Ab initio calculations

We present ab initio calculations on the atomic structure of the Sb-induced Si(111)-(5 root 3 x 5 root 3)R30 degrees surface. The scanning tunneling m icroscopy images of Si and Sb adatom structures are calculated and compared with recent experimental results. We demonstrate that the majority adatoms observed in the (5 root 3 x 5 root 3)R30 degrees structure are Sb atoms, s upporting the recently proposed atomic model [Park ct al., Phys. Rev. B 55, 9267 (1997)]. The origin of bias voltage-dependent scanning tunneling micr oscopy images is discussed.