MOPAC Calculation on Radicals

From: steve_rogers-0at0-ici.com
Subject: MOPAC Calculation on Radicals
Date: Mon, 1 Mar 1999 17:48:46 +0000

 Hi,
 I'm interested in trying to model free radical alkene polymerisation reactions
 using MOPAC (AM1, PM3).  There appear to be two possibilities for calculations
 on radicals - the Dewar half-electron method (which is invoked by the keyword
 DOUBLET) and UHF.   The results differ by a few kcal/mol.
 Can anyone advise me which option is likely to give the best results for
 reaction thermodynamics and activation energies of a radical adding to a double
 bond?  I'd also be interested in any comments on bond dissciation energies
 estimated by these methods.  I'll summarise any replies.
 Thanks,
 Steve Rogers
 email: steve_rogers-0at0-ici.com