The termination of the lower terrace at atomic steps on the 7 x 7 (111) surface was investigated by means of scanning tunnelling microscopy. It was suggested that 7 positions of the steps, relative to a 7 x 7 unit mesh of the end of the lower terrace, were possible for each of 2 step directions. Ten of them were observed, and a rule was proposed for termination at the steps.

H.Tochihara, W.Shimada, M.Itoh, H.Tanaka, M.Udagawa, I.Sumita: Physical Review B, 1992, 45[19], 11332-5