Showing papers by "Jens K. Nørskov published in 1990"
TL;DR: In this article, a model based on the effective medium theory of the oxygen-induced reconstruction of the (110) and (100) surfaces of Cu is presented, and equilibrium structures are calculated from a minimization of the total energy of the system.
Abstract: A model calculation based on the effective-medium theory of the oxygen-induced reconstruction of the (110) and (100) surfaces of Cu is presented. Equilibrium structures are calculated from a minimization of the total energy of the system. Missing-row-type reconstructions are found to be most stable in both cases, and an analysis is presented, showing what the driving force is behind these reconstructions.
116 citations
TL;DR: In this paper, an unambiguous structural model for the Cu(110)-c(6\ifmmode\times\else\texttimes\fi{}2) surface reconstruction is derived with ten Cu atoms within the c(6''ifmmodes''times''else''texttimes''fi{}) unit cell, two of which form a superstructure.
Abstract: From an interplay between scanning tunneling microscopy, surface x-ray-diffraction experiments, and theoretical predictions, an unequivocal structural model for the Cu(110)-c(6\ifmmode\times\else\texttimes\fi{}2)O surface reconstruction is derived with ten Cu atoms within the c(6\ifmmode\times\else\texttimes\fi{}2) unit cell, two of which form a Cu superstructure. A general picture evolves in which the present as well as the Cu(110)-(2\ifmmode\times\else\texttimes\fi{}1)O and the Cu(100)-(2 \ensuremath{\surd}2 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}2 )R45\ifmmode^\circ\else\textdegree\fi{}O reconstructions are stabilized by Cu-O-Cu chains directed along the [001] direction. The nucleation and growth of the c(6\ifmmode\times\else\texttimes\fi{}2) structure occur preferentially at steps.
113 citations
TL;DR: This work uses the observation that only very small changes in bond length with particle size are found, but the motion in the small particles is very anharmonic to resolve the current experimental controversy about the existence of bond contraction for small metal particles.
Abstract: A theoretical analysis is made of the bond lengths of small (100--1000 atoms) Cu particles at various temperatures. The interatomic interactions are calculated using the effective-medium theory and the finite-temperature properties obtained from a molecular-dynamics simulation. We find only very small changes in bond length with particle size, but the motion in the small particles is very anharmonic. We use this observation to resolve the current experimental controversy about the existence of bond contraction for small metal particles.
79 citations
59 citations
TL;DR: In this article, it is shown that the trap strengths are determined mainly by the interstitial electron density, and any open structure in the lattice leads to a trap, with the vacancies and voids being the strongest traps.
Abstract: From an interplay between theory based on the effective-medium scheme and experiments, an extremely simple picture has evolved which is capable of describing a vast number of experimental quantities related to interaction of hydrogen with metals, especially the trapping of hydrogen at defects. It is shown that the trap strengths are determined mainly by the interstitial electron density, and any open structures in the lattice leads to a trap, with the vacancies and voids being the strongest traps. It is also found theoretically and experimentally that up to six hydrogen atoms can be accomodated in a vacancy, and the change in trap strengths with occupancy has been determined. Recent results for the trapping of deuterium to defects in Pd are discussed.
18 citations
TL;DR: In this article, the authors measured the vibrational spectra of CO in the presence of coadsorbed Xe on Ru(001) and found that Xe induces CO stretch frequency downshifts as large as 38 cm −1.
18 citations
TL;DR: In this paper, the surface phonons of Cu(111) were studied using the effective medium theory to calculate the inter-atomic interactions, and Dispersion relations in excellent agreement with experiment were derived.
15 citations