Using the first-principles molecular-dynamics method in the energy-minimiza
tion application, we calculate the detailed geometry of Ga decamers on the
Si(lll) surface observed by scanning tunneling microscopy (STM). The calcul
ated relative heights of Ga adatoms agree reasonably well with STM data. Ou
r total-energy results support the Ga-Si honeycomblike triangular decamer m
odel proposed by Lai and Wang [Phys. Rev. B 60, 1764 (1999)] to explain the
Ga clusters observed in their STM measurements.