Summary: polarizability and vdW radius for B

 Dear CCLers,
 A few weeks ago, I asked for a value for the  polarizability
 and the van der Waals radius for B in a covalently bonded state.
 I would like to thank Wayne Steinmetz, Ajit J. Thakkar, and
 Robert J. Doerksen for their helpful replies.
 Wayne Steinmetz pointed me to the Allinger force field, which uses
 a van der Waals radius of 2.150 for covalently bonded B in the MM3 force
 field.  The epsilon value is 0.014 kcal/mole.
 Ajit Thakker suggested the following papers:
 Das and Thakkar, J. Physics B, 31 (1998) 2215, for the polarizability of
 a free boron atom, while the polarizability of a boron atom in a
 heteroatomic molecule can be found from the parameters for model 5 in the
 1998 JPCA paper by RJ Doerksen and AJ Thakkar (see below).
 Robert Doercksen pointed me to work from his Ph.D. thesis:
 "Azaborinines: Structures, vibrational frequencies, and
 polarizabilities,"
 J. Phys. Chem. A 102, 4679-4686 (1998), RJ Doerksen and AJ Thakkar.
 In further work coming out in JPCA in 1999, their additive atom model of
 polarizability for 104 planar heteroaromatic molecules containing 5 or 6
 of B, C, N, and O -- fitted to ab initio MP2 polarizabilities with an
 optimized basis set -- suggests that the polarizability of Boron in a
 planar heteroaromatic ring is about 15 a.u.
 Best regards,
 Tanja
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      Tanja van Mourik
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      University College London        work:   +44 (0)171-504-4665
      Christopher Ingold Laboratories  home:   +44 (0)1895-259-312
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      London WC1H 0AJ                  work: T.vanMourik # - at - # ucl.ac.uk
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