The Ge(001) surface reconstruction: DFT and MCS

The problem of relative energetic stabilities of the high order reconstructions of the Ge(001) surface is revisited by a more refined first-principles calculation based on density functional theory. Using this result, we performed a Monte Carlo simulation of the phase transition, and obtained 315 K as the transition temperature of p(2 x 1) --> c(4 x 2). This reproduces fairly well the transient temperature (250-350 K) observed by an X-ray diffraction experiment. The obtained geometry of the c(4 x 2) structure compares well with an X-ray diffraction experiment. The potential energy curves of flip-flop motions of both single dimer and dimer in type-P defect are also obtained.