Two prototypes of metal adatom configurations on Mo(1 1 2): an ab initio study for Li and Co

By means of the ab initio cluster expansion technique two prototypes of metal adatom configurations on Mo(1 1 2) are found. For the big Li atoms the interaction coefficients along (across) the furrows of the surface are strongly repulsive (attractive) and the ground state configurations are arrangements of monatomic chains. For the smaller Co atoms all dominant interaction coefficients are attractive and the ground state is a heterogeneous phase consisting of large patches of occupied or unoccupied surface sites. A hypothesis is raised that stable magnetic atomic chains on (1 1 2) surfaces of bcc transition metal substrates probably are formed only for rare-earth adatoms.