Help With Gaussian 98 Hindered Rotor Calculations



Hello,

 

I am trying to use the hindered rotor approximation for frequency calculations on benzyl radicals such as styrene radicals.  I am using Gaussian 98 with G3//B3LYP level of theory.  When using the command freq=hindrot after geometry optimization is complete, Gaussian crashes with the error message “problem with the number of degrees of freedom”.  If I replace the radical with a hydrogen (e.g. toluene or styrene) I have no problems completing the calculations.

 

Does anyone have any suggestions/experience with this?

 

Thanks much