Model potential for the dimer system on the Si(001) surface improved by a first-principles calculation and structural fluctuation studied by a Monte Carlo simulation

The improved model potential of the dimer system on Si(001) surface is obtained based on the results of the first-principles calculation (FPC). The transition rates of the dimer flip-flop motion are obtained from the model potential. The time-resolving dynamical Monte Carlo simulations (TDMCS) on Si(001) surface at 70 K for the orientational arrangement are performed. The time series of the time-averaged local order parameter for c(4 × 2) structure are calculated from the results of TDMCS. The time series are shown to reproduce well the results of time-resolving constant-height current mode STM observed at 70 K. The improved model potential is confirmed to be well effective.