TPS62868: PSPICE simulation over frequency to extract output impedance

Tool/software:

Buck or PSPICE team,

We have a customer trying to use the PSPICE model in frequency simulation to extract the output impedance. 

Questions from them:

Is there an app note to extract output impedance using TI’s models specifically for PSPICE?

Can we use the TPS628680A PSPICE model provided by TI to get the closed-loop output impedance?

Thanks,
Darren