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Shape transition of medium‐sized neutral silicon clusters
Author(s) -
Sieck A.,
Frauenheim Th.,
Jackson K. A.
Publication year - 2003
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200301886
Subject(s) - silicon , cluster (spacecraft) , chemical physics , diamond , atom (system on chip) , diamond cubic , cluster size , atomic physics , crystallography , materials science , molecular physics , chemistry , molecular dynamics , computational chemistry , physics , optoelectronics , computer science , embedded system , composite material , programming language
Addressing the shape transition of silicon clusters, indicated by mobility experiments on silicon cluster cations with 24 to 30 atoms, we investigate the structure of low energy neutral silicon clusters with 25, 29, and 35 atoms within a density‐functional based tight‐binding approach. Since there is strong evidence for several nearly degenerate low‐energy isomers for clusters of this size, we perform an extensive, but limited global search with Simulated Annealing and statistically analyze for each cluster size the 100 clusters with the lowest energy. We find different dominant shapes in the set of low energy clusters for each size. For neutral silicon clusters with 25 atoms, both prolate and spherical structures with low cohesive energies exist. For clusters containing 29 or 35 atoms, the low‐energy isomers exhibit a spherical shape. For each cluster size several stable isomers with similar shapes, and hence similar mobilities, but different bonding patterns exist. The most stable 25 atom cluster resulting from our global search has the lowest energy within DFT‐GGA known so far. Finally, we investigate the transition to diamond‐like bonding patterns expected for larger silicon clusters. Clusters with up to 239 atoms resemble amorphous silicon rather than the diamond structure and contain several highly coordinated atoms. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)