how to simulate the Q value of on-chip inductor using spectr

The foundry should have inductors of a useful range already characterized in its library for use. For example, the SiGe process by IBM comes with inductors ranging from 0.6nH to 15.8nH.
If not, just layout the turns and count the number of squares of metal used and use that resistance in your sim. Of course, use top metal to mimize the dielectric loss of oxide and substrate.

simulate one port inductor, that is, connect the one port of the inductor to ground.

Using AC simulation, you can get the impedance of inductor.

the Q factor of inductor is just imag(Z)/real(Z).

that's all. of course, it's different according to the frequency.

Good luck.