Abbreviated Journal Title
Phys. Rev. B
SCANNING-TUNNELING-MICROSCOPY; CU(100)-C(2X2)N SURFACE; PHONON-DISPERSION; SELF-ORGANIZATION; RECONSTRUCTION; CU(100); LEED; IMAGES; ENERGY; CU(100)C(2X2)-N; Physics, Condensed Matter
Helium-atom scattering and density-functional perturbation theory (DFPT) calculations invoking the linear-response approximation and the pseudopotential approach have been used to study the vibrational dynamics of c(2x2)-like phases produced by nitrogen-ion implantation and subsequent annealing of Cu(001) surfaces. We find that, while the c(2x2) phonon dispersion relations are different from those of clean Cu(001), neither the acoustic nor the optical surface phonon mode energies measured along both  and  directions are dependent on N coverage once the c(2x2) pattern is formed. We show that the dispersion of the surface phonon modes is well reproduced with an analysis of the DFPT calculations of a nonstress relieved c(2x2) structure. A marked softening of a zone center optical mode is very apparent both experimentally and in the calculations. We show this softening arises largely because of interplanar Cu surface relaxations induced by N adsorption.
Physical Review B
Ciftlikli, E. Z.; Goncharova, L. V.; Hinch, B. J.; Ortigoza, Marisol Alcántara; Hong, Sampyo; and Rahman, Talat S., "Vibrational dynamics of a c(2x2) phase induced by nitrogen adsorption on Cu(001)" (2010). Faculty Bibliography 2010s. 47.