Theoretical study on the structural phase transition of Si(1 1 1)3×3-Ag surface

We study the arrangement of Ag atoms of the Si(1 1 1)3×3-Ag surface by Monte Carlo simulations (MCS). For this purpose, an adiabatic potential for Ag atoms representing short-ranged interactions including three-body terms is proposed, and the parameters in it are derived from results of first-principles calculations. We perform MCS with this potential and show that the surface undergoes an order–disorder phase transition with respect to the arrangement of Ag atoms. The transition temperature estimated by the present MCS is consistent with results of scanning tunneling microscopy (STM) observations. Calculated STM images based on results of MCS clearly show that the observed STM images with a honeycomb pattern are well understood by the fluctuation of Ag atoms.