smearing and DIIS values - Dmol3

Hi all,

I'm trying to do calculation for B2O3, it always gave me the error below:

" Message: SCF not converging. Choose larger smearing value in DMol3 SCF panel

or modify/delete "Occupation  Thermal" in the input file.

You may also need to change spin or use symmetry."

Is there any one can help me to know the best values for an insulator ( which has larg band gap ) such B2O3.

Any help would be appreciated.

Thanks

Niveen