Hello, I am working with the HF solver in CST Studio 2021. I would like to define a material with the second order general dispersion model, but need to use a negative value for the a1 coefficient. Unfortunately, if I try to set any negative parameters, an error appears. I would like to do this in order to gradually change the material dispersion from drude-like to lorentz-like. Any suggestions on how to achieve this?

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