Vibron-vibron coupling from ab initio molecular dynamics simulations of a silicon cluster

We study the temperature-dependent dynamical processes of a Si10H16 cluster and obtain a blue shift of the Si-Si vibrational modes with transverse acoustic character and a red shift of the other vibrational modes with increasing temperature. We link this behavior to the bond length expansion and the...

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Bibliographic Details
Published in:	New journal of physics Vol. 15; no. 4; pp. 43039 - 14
Main Authors:	Han, Peng, Vil iauskas, Linas, Bester, Gabriel
Format:	Journal Article
Language:	English
Published:	IOP Publishing 22-04-2013
Subjects:	Blue shift Clusters Computer simulation Coupling (molecular) Doppler effect Molecular dynamics Occupation Strength
Online Access:	Get full text
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Summary:	We study the temperature-dependent dynamical processes of a Si10H16 cluster and obtain a blue shift of the Si-Si vibrational modes with transverse acoustic character and a red shift of the other vibrational modes with increasing temperature. We link this behavior to the bond length expansion and the varying sign of the Grüneisen parameter. We further present a computational approach able to extract the vibron-vibron coupling strength in clusters or molecules. Our approach is based on ab initio Born-Oppenheimer molecular dynamics and a projection formalism able to deliver the individual vibron occupation numbers. From the Fourier transform of the vibron energy autocorrelation function, we obtain the coupling strength of each vibron to the most strongly coupled vibronic states. We find the vibron-vibron coupling strength up to 2.5 THz with a moderate increase of about 5% when increasing the temperature from 50 to 150 K.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1367-2630 1367-2630
DOI:	10.1088/1367-2630/15/4/043039