How to define a metal in the Eigenfrequency analysis?

Hi, I want to define a metal material (i.e. Ag or Au) in the RF Eigenfrequency analysis. I may defiene by typing in the Drude model, but how can I connect the omega in my equations to the readable omega of comsol? In mode analysis, this can be specify using the frequency definition of 'nu_rfwv', but in Eigenfrequency, what should I do?

p.s. My version is still COMSOL 3.5a.

Thanks in advance.

Xiang