The potential energy landscape of a monolayer adsorbed on well-ordered (111) surface is analyzed for periodic cells with a variable number of adsorbate $\left(N_{\mathit{ads}}\right)$ and substrate $\left(N_{\mathit{sub}}\right)$ particles. The atom-surface potential is described by the first Fourier series term with variable corrugation, while the lateral interaction in the monolayer is modeled by a repulsive exponential term. Special attention is devoted to the determination of the total number of minima for given $N_{\mathit{ads}}$ and $N_{\mathit{sub}}$ and the probability of relaxation to the global minimum in each of the unit cells, as well as the construction of the lowest energy versus coverage curve as a function of the atom-surface potential corrugation. We find that the global appearance of the energy landscape in the majority of the unit cells is particularly simple, characterized by the global minimum positioned in a very wide basin and the high-energy minima forming a tail structure. However, this rule is broken for several unit cells when the corrugation of the atom-surface potential becomes large, making the location of the global minimum a rather difficult task. Despite the simplicity of our model, phase transitions from commensurate to striped incommensurate to hexagonal incommensurate rotated structures are observed.

• Received 5 October 2006

DOI:https://doi.org/10.1103/PhysRevB.75.085420