Molecular-dynamics simulation of crystalline 18-crown-6: thermal shortening of covalent bonds

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Eerden, J. van and Harkema, S. and Feil, D. (1990) Molecular-dynamics simulation of crystalline 18-crown-6: thermal shortening of covalent bonds. Acta crystallographica Section B: Structural science, 46 . pp. 222-229. ISSN 0108-7681

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Abstract:Molecular-dynamics simulations of crystalline 18-crown-6 have been performed in a study of the apparent thermal shortening of covalent bonds observed in crystal structures. At 100 K, a shortening of 0.006 _+ 0.001 A for C----C and C----O bonds was obtained. This result was found to be independent of details of the force field and the simulation. There was agreement between computational and experimental values for the thermal parameters, as well as for the molecular geometry (bond and dihedral angles) of 18-crown-6. Some differences are attributed to the inability of the force field to reproduce hydrogen-bonding geometries. Simulation at 295 K resulted in an estimated shortening of 0.019_+ 0.005 A. Thus at room temperature for C--C bonds (apparent) thermal shortening and (real) chemical shortening, resulting from the electronegative oxygen substituents, are of the same order of magnitude. In the simulation at 295 K occasional dihedral transitions were observed, which may reflect the proximity of the melting point (312 K).
Item Type:Article
Copyright:© 1990 The International Union of Crystallography
Link to this item:http://purl.utwente.nl/publications/59219
Official URL:http://dx.doi.org/10.1107/S0108768189011560
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