97 research outputs found
Self-diffusion of adatoms, dimers, and vacancies on Cu(100)
We use ab initio static relaxation methods and semi-empirical
molecular-dynamics simulations to investigate the energetics and dynamics of
the diffusion of adatoms, dimers, and vacancies on Cu(100). It is found that
the dynamical energy barriers for diffusion are well approximated by the
static, 0 K barriers and that prefactors do not depend sensitively on the
species undergoing diffusion. The ab initio barriers are observed to be
significantly lower when calculated within the generalized-gradient
approximation (GGA) rather than in the local-density approximation (LDA). Our
calculations predict that surface diffusion should proceed primarily via the
diffusion of vacancies. Adatoms are found to migrate most easily via a jump
mechanism. This is the case, also, of dimers, even though the corresponding
barrier is slightly larger than it is for adatoms. We observe, further, that
dimers diffuse more readily than they can dissociate. Our results are discussed
in the context of recent submonolayer growth experiments of Cu(100).Comment: Submitted to the Physical Review B; 15 pages including postscript
figures; see also http://www.centrcn.umontreal.ca/~lewi
Atomic-scale structure of dislocations revealed by scanning tunneling microscopy and molecular dynamics
One-dimensional nanoclustering of the Cu(100) surface under CO gas in the mbar pressure range
The bulk terminated Cu(100) surface becomes unstable in the presence of CO at room temperature when the pressure reaches thembar range. Scanning tunneling microscopy images showthat above 0.25mbar the surface forms nanoclusters with CO attached to peripheral Cu atoms. At 20 mbar and above 3-atom wide one- dimensional nanoclusters parallel to b001N directions cover the surface,with CO on every Cu atom, increasing in density up to 115 mbar. Density functional theory explains the findings as a result of the detachment of Cu atoms fromstep edges caused by the stronger binding of CO relative to that on flat terraces
Britain and West Germany in the 1970's - the economic dimension of the political relationship
SIGLEAvailable from British Library Document Supply Centre- DSC:D88665 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Experimentelle Untersuchung der Strömung in einer Unterschall-Axialverdichterstufe bei hoher Drosselung und im Rotating-Stall
Radiale Mischung in Axialverdichtern : Bedeutung und experimentelle Methoden zu ihrer Erfassung
Experimentelle Untersuchung der Strömung in einer Unterschall-Axialverdichterstufe bei hoher Drosselung und im Rotating-Stall
Experimentelle Untersuchung der Struktur des Rotating Stall in einer Unterschall-Axialverdichterstufe
Untersuchung des Abreissverhaltens im Laufrad einer Axialverdichter-Stufe : Arbeitsbericht zum Forschungsvorhaben 'Gitterbelastungskriterien für instationäre Strömungen'
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