Selenium Adsorption at Different Coverages on Fe(100) and Fe(111): A DFT Study

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

APPLIED SURFACE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 315 p. 252 - 260

0169-4332

Se adsorption on Fe(100) and (111) surfaces is examined using the density functional theory (DFT). Selenium is adsorbed in a distorted bridge on the (111) surface while in the (100) surface it 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 the (100) plane for ¼ and ½ ML coverage and some relaxation at 1 ML (4.5%). Contraction increases to 15% for the (111) plane at ¼ ML. At a higher coverage, there is a non-regular movement of surface metal atoms, and there is almost no change at 1ML. The magnetic moment for surface Fe atoms decreases with coverage. The most important changes are in the (100) plane, followed by the (110) and then the (111) planes with a reduction of 52, 24 and 7% respectively. The density of states presents a contribution of Se states at -5.0 eV and -13.1 eV, when stabilized after adsorption. The Fe-Fe bond weakening is higher in the (100) plane. Fe-Se bonds are formed at the expense of the metallic bond.