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Molecular Origins of the Unique Conformational Properties of the Polysilanes: A Molecular Dynamics Study of Poly(Di-N-Hexylsilane)

Published online by Cambridge University Press:  26 February 2011

William J. Welsh ,
Samuel H. Tersigni  and
Wangkan Lin
William J. Welsh
Affiliation:
Department of Chemistry, University of Missouri-St. Louis, St. Louis, MO 63121
Samuel H. Tersigni
Affiliation:
Department of Chemistry, University of Missouri-St. Louis, St. Louis, MO 63121
Wangkan Lin
Affiliation:
Department of Chemistry, University of Missouri-St. Louis, St. Louis, MO 63121
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Abstract

The conformational dynamics of a model compound for poly(di-n-hexylsilane) (PDHS) has been explored using the new molecular dynamics program MM3-MD. MM3-MD trajectories at variable temperatures reveal two abrupt conformational transitions, one near -182°C and another near -175°C, associated with two energy barriers on the potential-energy surface. The first transition near -182°C allows shifts in the backbone torsion angle from that defined by the global energy minimum designated off-trans to that corresponding to a statistical collection of torsion angles within the range trans ±30°. The second transition near -175°C allows the backbone torsion angle to explore the remainder of its torsional space. The sidechain dynamics follows a similar pattern. We suggest that the abrupt transition calculated here at -182°C for “gas.phase” PDHS corresponds to that observed for PDHS at -28°C in solution and at 42°C in the solid state.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 278: Symposium W – Computational Methods in Materials Science , 1992 , 55
Copyright
Copyright © Materials Research Society 1992

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References

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