Density Functional Theory study of Selenium adsorption on Fe(110)

E. A. GONZÁLEZ, P. V. JASEN, M. SANDOVAL, P. BECHTHOLD, A. JUAN, B. SETINA BATIC, M. JENKO

APPLIED SURFACE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2011 vol. 257 p. 6878 - 6883

0169-4332

The adsorption of atomic Se on the Fe(110) surface is examined using density functional theory (DFT). Selenium is adsorbed in the high-symmetry adsorption sites: bridge (short and long), and atop sites at coverages of ½ , ¼ and 1 monolayer (ML). The long bridge (LB) site is found to be the most stable, followed by the short bridge (SB) and top sites (T). The following overlayer structures were examined, p(2x2), c(2x2) and p(1x1), which correspond to ¼ ML, ½ ML and 1 ML respectively. The adsorption energy is -5.23eV at ¼ ML. The Se adsorption results in a surface reconstruction, being more extensive for adsorption in the long bridge site at ½ ML, with vertical displacements between + 8.63 and -6.69 % ( relative to the original Fe position), affecting the 1st and 2nd neighbours. The largest displacement in the x or y-directions was determined to be 0.011, 0.030 and 0.021 Å for the atop and bridge sites. Comparisons between Se-adsorbed and pure Fe surfaces revealed reductions in the magnetic moments of surface-layer Fe atoms in the vicinity of the Se. At the long bridge site, the presence of Se causes an decrease in the surface Fe d-orbital density of states between 4 and 5 eV below the Fermi level. The density of states present a contribution of Se states at -3.2 eV and -12.9 eV stabilized after adsorption. The Fe-Fe overlap population decrease and a Fe-Se bond are formed at expenses of the metallic bond.