Hi Miguel,
These parameters relate to how the relative permittivity and conductivity of the APML material varies as function of distance to the simulation domain boundary. Generally the default options work very well, but if you would like to make changes and understand their meaning I recommend the section 5.5.2 in the following textbook, which is the main reference used.
Taflove, A., “Advances in Computational Electrodynamics—The Finite-Difference Time-Domain
Method”, Artech House, Boston, Ch. 5, (1998).
I attached a snapshot of our documentation that relates the conductivity to the distance inside the APML and also Kmax, which is the Real APML Tensor Parameter.
Regards
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