{ital Ab initio} calculations of Ru, Pd, and Ag cluster structure with 55, 135, and 140 atoms

Journal Article · Sat Feb 01 04:00:00 EST 1997 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.473339· OSTI ID:463520

Jennison, D R ^[1]; Schultz, P A; Sears, M P ^[2]

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1. Surface and Interface Sciences Department 1114, Sandia National Laboratories, Albuquerque, New Mexico 87185-1413 (United States)
2. Parallel Computational Sciences Department 9225, Sandia National Laboratories, Albuquerque, New Mexico 87185-1111 (United States)

A massively parallel {ital ab initio} computer code, which uses Gaussian bases, pseudopotentials, and the local density approximation, permits the study of transition-metal systems with literally hundreds of atoms. We present total energies and relaxed geometries for Ru, Pd, and Ag clusters with N=55, 135, and 140 atoms. The N=55 and 135 clusters were chosen because of simultaneous cubo-octahedral (fcc) and icosahedral (icos) subshell closings, and we find icos geometries are preferred. Remarkably large compressions of the central atoms are observed for the icos structures (up to 6{percent} compared with bulk interatomic spacings), while small core compressions ({approximately}1{percent}) are found for the fcc geometry. In contrast, large surface compressive relaxations are found for the fcc clusters ({approximately}2{percent}{endash}3{percent} in average nearest neighbor spacing), while the icos surface displays small compressions ({approximately}1{percent}). Energy differences between icos and fcc are smallest for Pd, and for all systems the single-particle densities of states closely resembles bulk results. Calculations with N=134 suggest slow changes in relative energy with N. Noting that the 135-atom fcc has a much more open surface than the icos, we also compare N=140 icos and fcc, the latter forming an octahedron with close packed facets. These icos and fcc clusters have identical average coordinations and the octahedron is found to be preferred for Ru and Pd but not for Ag. Finally, we compare Harris functional and LDA energy differences on the N=140 clusters, and find fair agreement only for Ag.

• Research Organization: Sandia National Laboratory
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 463520
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 5 Vol. 106; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ATOMIC CLUSTERS
ELECTRONIC STRUCTURE
FUNCTIONAL MODELS
FUNCTIONALS
GEOMETRY
MORPHOLOGY
PALLADIUM
RUTHENIUM
SILVER
SOLID CLUSTERS
density functional theory
pseudopotential methods