HFSS SMD capacitor simulation?

What is the best way to simulate several pF SMD capacitors on microstrip line circuits?
Are there some precise mesh/material libraries/constructors available anythere to import and place on the structure to be simulated?

OK. If there's no way to simulate real meshed capacitor, what is the "right" way for equivalent capacitance?

1)PLANAR(rectangle) insertion in microstrip gap with "Lumped RLC" BOUNDARY properties (C=xx pF)
2)PLANAR(rectangle) insertion in microstrip gap BETWEEN two large plates with "Lumped RLC" BOUNDARY properties (C=xx pF)
3)3D(box) insertion in microstrip gap with "Lumped RLC" BOUNDARY properties (C=xx pF)
4)3D(box) insertion in microstrip gap BETWEEN two large plates with "Lumped RLC" BOUNDARY properties (C=xx pF)

5)PLANAR(rectangle) insertion in microstrip gap with LUMPED PORT properties (Reactance)
6)PLANAR(rectangle) insertion in microstrip gap BETWEEN two large plates with LUMPED PORT properties (Reactance)
Is impedance of the port in (5)(6) React=-1/(ωC)?