CCL:G: frontier orbital of ionic liquids

 Sent to CCL by: "Dornoo  Sharnod" [rina.dao ..]
 hi, all
 I have been computing properites of some ionic liquids of N-methyl pyridine type
 cation and some anions( namely BF4-, PF6-, and AlBr4-). It happens that, the
 structures are all similar at the same basis set, but the orbitals show much
 difference. The LUMO of the ionic liquids with the PF6- and AlBr4- almost lie on
 the anions, while the M-Pyridine BF4- ionic liquid has a LUMO that locates on
 the cation.
 I use gaussian 03, a b3lyp/6-31g(d,p) calculation. I don't know what it
 indicates. does it have to do with the method or basis set ? I can't make sure
 the phenomenon is due to the difference of the molecular properties or just came
 > from the method ? Could anyone help me with an advice?
 thank you ~