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Internal vibrations of a molecule consisting of rigid segments. I - Non-interacting internal vibrationsFor molecular crystals, a procedure is proposed for interpreting experimentally determined atomic mean square anisotropic displacement parameters (ADPs) in terms of the overall molecular vibration together with internal vibrations with the assumption that the molecule consists of a set of linked rigid segments. The internal librations (molecular torsional or bending modes) are described using the variable internal coordinates of the segmented body. With this procedure, the experimental ADPs obtained from crystal structure determinations involving six small molecules (sym-trinitrobenzene, adenosine, tetra-cyanoquinodimethane, benzamide, alpha-cyanoacetic acid hydrazide and N-acetyl-L-tryptophan methylamide) have been analyzed. As a consequence, vibrational corrections to the bond lengths and angles of the molecule are calculated as well as the frequencies and force constants for each internal torsional or bending vibration.
Document ID
19930055705
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
He, X. M.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Craven, B. M.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Acta Crystallographica. Section A: Foundations of Crystallography
Volume: 49
ISSN: 0108-7673
Subject Category
Chemistry And Materials (General)
Accession Number
93A39702
Distribution Limits
Public
Copyright
Other

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