Good day, Holger. I would like to help. But could you describe shortly, what is problem to implement Vp in a .model statement? I am not so deeply familiar with the spice-engine. I have the original article that LTspice is based about the Vp parameter, so I can try to dig into it...
Good day. I just realized (may be too late) some my article in the discussion. All SW and its sources related to it can be found on ResearchGate: https://www.researchgate.net/publication/283824585_Basic_diode_SPICE_model_extension_and_a_software_characterization_tool_for_reverse_recovery_simulation Also some preprint (note to myself) using another approach to simulate reverse recovery: https://doi.org/10.36227/techrxiv.14915139.v2 with free sw tool also.