Drude Model calculations for Gold/Silver??

I want to design a nano antenna in CST MWS at center frequency of 191 THz or 1500nm. I read that at optical frequencies metal behave like plasmons and the material properties are calculated via Drude Model. I wanted to ask following;

1) What is this Drude model?
2) How can I calculate the material (Au/Ag) properties with Drude model? Formulas??
3) Are there any constant values for Gold and Silver calculated via Dride Model? As I found different values in diff papers??? [a] [b]
4) How are the plasmonic frequency and scattering frequencies calculated at THz range via Drude model?
5) What is epsilon infinity values in CST for working with Drude model??


[a] http://ieeexplore.ieee.org/stamp/sta...umber=06656480
[b] http://ieeexplore.ieee.org/xpl/artic...number=6250087

Awaiting positive replies,

Regards