Determination of the Cu(110)-c(6X2)-O structure by x-ray diffraction

We have performed a structural determination of the Cu(110)-c(6 X 2)-O surface by x-ray diffraction. A model including only copper atoms is found on the basis of the Patterson function; the positions of the oxygen atoms are revealed in an electron-density-difference map. The final structure has a reduced mean-square residual of chi-2 = 1.9, and includes most of the features known from the literature, with 5/6 of a monolayer of Cu atoms considerably displaced away from ideal lattice sites, two different oxygen sites, and an oxygen coverage of 2/3 of a monolayer. The structure contains Cu-O chains as found on the Cu(110)-(2 X 1)-O and Cu(100)-(square-root 2 X 2 square-root 2)R 45-degrees-O surfaces, but they are more densely packed than in the 2 X 1 structure.