MPSH of Benzen molecule in Silicon electrode.

[hieido]

Dear all,
I have a question about H-L Band Gap in MPSH calculation.
 
I tried to Calculate the MPSH of benzen in Silicon electrode under different bias,
usually, the Band-gap HOMO-LUMO of molecule benzen in Device junction would not change event under different applied bias right?

But in my case, with silicon electrode, the H-L band gap changed under different applied bias. I can't understand .... why it becomes like this??
Please help me!

[Anders Blom]

It can certainly change, it's why one cannot deduce properties of the transmission spectrum only from a zero-bias calculation.