drude model solver

I want to simulate the scattering properties of Au or Ag nanosphere (Drude Model) by using CST Microwave Studio, and calculate the Absorption, Scattering and Extinction Cross section efficiency, but in the simulation, I find that when I use the Transient solver, the results for E and H are completly different from that got from the frequency model solver, so I want to why these happen and How can I improve my results by using transient solver?
Thanks!
Y Xiang

I am not a CST user, but I guess depending on the rise time and signal period, you must define the frequency bandwidth large enough to cover all the transient information.

wlcsp