Amber force field parameters for bromine



Hello all,
 My group is interested in doing molecular dynamics on a system
 including a molecue with bromine covalently bound with an aromatic
 carbon.  The only parameters for bromine that seem to be included
 in the Amber force field are for counter-ions.  Does anyone have a
 reference (journal, web, crayon on a napkin, whatever) for covalent
 bromine parameters?
 Thanks,
 Matt Zwier
 --
 Matthew Zwier (matthew.zwier "-at-" hope.edu)
 Department of Chemistry Undergraduate Researcher
 Hope College, Holland, MI