3nm x 3nm STM image of the Cu(014)-O 0.5ML surface measured with MnNi tip. Cu(014)-O surface consists of four-atom wide (001) terraces of 0.72 nm width separated by monatomic steps. The presented image demonstrates doubling of the atomic features along the close-packed direction: one can find 8 features inside the terraces instead of four. The separation between closest maxima in the image is around 130 pm. Clearly seen double protrusions of each copper atom are observed because of asymmetric electronic structure of the MnNi tip which at some tunnelling parameters works like an effective twinned tip. A single-atom defect demonstrates the sharpness of the tip. This result has been discussed in Phys. Rev. Letters, 98, 206101 (2007) (A.N.Chaika, V.N.Semenov, S.S.Nazin, S.I.Bozhko, S. Murphy, K. Radican, I.V.Shvets, "Atomic Row Doubling in the STM Images of Cu(014)-O Obtained with MnNi Tips"). Image courtesy of A.Chaika. The image was measured in constant current mode using RT STM GPI-300.