Evidence for the Formation of Different Energetically Similar Atomic Structures in Ag(111)−(√7×√7)−R19.1°−CH3S

The atomic structure and thermodynamic stability of Ag ( 111 ) ( √ 7 × √ 7 ) − R 19.1 ° − CH 3 S has been studied by means of density functional calculations and atomistic first principles thermodynamics. The unreconstructed model and two recently proposed reconstructions have been considered. It is found that, in spite of significant differences in the atomic structure, the different surface models have a very similar surface free energy. It is claimed that the different ordered phases can coexist and that the appearance of one or another depends on the external preparation conditions