Ceilidh ... BOND DISSOCIATION ENERGY in PCGAMESS

PC GAMESS/Firefly-related discussion club

BOND DISSOCIATION ENERGY in PCGAMESS - HELP!!!

I would like to ask about the consistency of using DFT methods in PCGAMESS to calculate Bond Dissociation Energy of Different Molecules. IM currently using B3LYP/6-31+G(3d,p,f) as my chosen method and basis set and I found out it computes the BDE Values of some compounds reasonably only if the involve radical is Hydrogen (H). However, when I tried to compute the BDE Values of compounds whose dissociation reactions involves other radicals aside from hydrogen (e.g CH3, SiH3), there is significant error in the results. There's a difference of about 6-10 kcals/mole with the computed values with the literature values. What could be the reason for this? Im looking at the capability of DFT methods on integrating electron correlation between molecules. Im also considering the size of the radicals formed. Am I at the right path? Please do help.

Mon Dec 8 '08 10:44am

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