Phase diagrams of adsorbate-induced missing row reconstructions on FCC(1 1 0) surfaces

Abstract

The phase diagrams of adsorbate-induced missing row reconstructions on FCC(1 1 0) surfaces, such as O/Pd(1 1 0) and O/Rh(1 1 0), are calculated by the Blume–Emmery–Griffith model. In the model, we introduce the interactions K xy ( J xy ) between the ( x, y)-distant neighboring adatoms (adatom–substrate dipoles), where ( x, y) is (1,0), (2,0) and (0,1). The calculation of the temperature versus adatom chemical potential phase diagram is performed using Monte Carlo simulations. It is indicated that (1) the topology of the phase diagram obtained by Monte Carlo simulations is almost same as that obtained by mean-field-approximation (MFA); (2) the values of transition temperatures, however, are nearly half as much as those in the MFA; (3) if the interactions K 10 ( J 10) and K 20 ( J 20) are competitive, there appear the modulated (incommensurate) phases below transition temperatures. The temperature-dependence of the kinematic LEED intensity is calculated.