In the new version of PCB SIM it is possible to stimulate the impedance with a trapezoidal waveform in the time domain. Therefore the waveform is generated with a fourier series and multiplied with the impedance in the frequency domain. The resulting spectrum is transferred back into the time domain.
It can give valuable insight in the bandwidth requirements of switched signals.
Another new feature is the creation of an equivalent circuit diagram for SPICE. You can rebuild the impedance of your PDN in SPICE and use it for Transient simulations.
You only need to add the subcircuit created by PCB SIM in LTspice.