DENSITY FUNCTIONAL STUDY OF SELENIUM ADSORPTION AT DIFFERENT COVERAGE ON Fe(100), (111) AND (110)

V. CARDOSO SCHWINDT; J. S. ARDENGHI; P. BECHTHOLD; E. A. GONZÁLEZ; P.V. JASEN; A. JUAN; B. SETINA BATIK; M. JENKO

Dubrovnik

Congreso; 16th International Conference on Thin Films; 2014

The Se adsorption on the Fe(100) and (111) surfaces is examined using density functional theory (DFT) and compared with previous calculations on (110). Selenium is adsorbed in a distorted bridge on the (111) surface while in the (100) prefers a 4-fold hollow site, with energies of -10.36 and -5.25 eV, respectively. Se adsorption results in surface reconstruction. There is some contraction in the case of (100) plane for 1⁄4 and 1⁄2 ML coverage and some relaxation at 1 ML (4.5%). The contraction increase to 15 % for the (111) plane at 1⁄4 ML. At higher coverage there is a non-regular movement of surface metal atoms, and there is almost no change at 1 ML. The magnetic moment for the surface Fe atoms decrease with the coverage. The most important changes appear is in the (100) plane, followed by (110) and then by (111) with a reduction of 52, 24 and 7% respectively. The density of states present a contribution of Se states at -5.0 eV and -13.1 eV, stabilized after adsorption. The Fe-Fe bond weakening is higher in the (100) plane. Fe-Se bond are formed at expenses of the metallic bond.