One additional comment: if you're going to rerun all of your calculations as Jim suggested, you should use one additional option:
$CONTRL D5=.T. $END
This selects the use of spherical functions, which is required for the 6-311G basis. Other sets included in Firefly (such as 6-31G and TZV) should not use this option.
On Wed Jun 26 '13 5:45pm, Xaiza wrote
>Dear Sir Thomas,
>I am very thankful to your insights, suggestions and for the effort of re-running my calculations. I will apply your suggestions in my recalculations. But I have a question sir. Would it be fine if some of my MP4 single point calculations have that keywords and some don't? That is, I'll only apply the keywords you have suggested on the molecules in which I have some problem with. I am bit worried about the energy differences that I would be obtaining, most especially since in some of my reactions, only in one molecule that I encountered this MP4 problem.
[ This message was edited on Thu Jun 27 '13 at 12:09pm by the author ]