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O: Fachverband Oberflächenphysik
O 36: Posters: Bio/organic Molecules on Surfaces, Graphene, Solid/liquid interfaces, Metal Substrates, Electronic Structure Theory
O 36.104: Poster
Dienstag, 1. April 2014, 18:30–22:00, P1
CPMD simulations of oxidized Si clusters — •Paul Schwarz1, Carola Kryschi2, and Bernd Meyer1 — 1Interdisciplinary Center for Molecular Materials and Computer-Chemistry-Center, FAU Erlangen-Nürnberg — 2Physical Chemistry, FAU Erlangen-Nürnberg
The oxidation of small Si clusters was studied by Car-Parrinello Molecular Dynamics (CPMD) simulations in order to obtain reasonable structures for oxygen-passivated clusters with a crystalline Si core with size of about 1 nm. The method of simulated annealing was applied to allow for atomic rearrangements and to find favorable low-energy configurations. The clusters were equilibrated at different temperatures, quenched to room temperature and finally relaxed. By increasing stepwise the amount of oxygen, four types of oxidized Si63 clusters with composition of Si63O24, Si63O32, Si63O48, and Si63O68 were obtained.
It is found that at low oxidation clusters with crystalline and amorphous
Si core are rather similar in energy.
The energy of the clusters is lowered by formation of free-standing SiO2
groups at the surface, under the condition that the crystalline core is
retained during the simulation.
These free-standing SiO2 groups could be precursors for the formation
of surface silanone groups.
The crystalline core is furthermore stabilized by increasing oxidation.
Finally, hydrogen and methyl groups were added at the surface of pure
and oxidized Si clusters, with the aim of finding vibrations that could
explain the vibronic structure in the photoluminescence spectra of
synthesized Si clusters.