Modify the relative permittivity and solve the Maxwell equations

[njust-csc]

Hello everyone. I want to use the PICMI format to specify the relative permittivity of a certain region to simulate a certain material, and then make this modification affect the calculation of the Maxwell equations.
I browsed warpx.readthedocs.io and found that the input file format can be used for modification, but I think this format is not as convenient to use as PICMI.
In addition, I saw that someone asked on the forum in 2024 about the method of implementing the macroscopic maxwell equation in PICMI, and the answer was that it would be developed.
So I want to know whether the method of solving the macroscopic maxawell equation is implemented in the PICMI format. If so, how is it implemented? If not, is there any other way to achieve this process?

[RemiLehe]

Thanks for the question.
At this point, the interface to the macroscopic Maxwell equation is still not implemented in the PICMI format.
The easiest/fastest way to set up a simulation with macroscopic Maxwell equations would be to use the input file format.

Implementing the interface in PICMI would involve adding a new class in picmi.py, similar to that one:
https://github.com/BLAST-WarpX/warpx/blob/development/Python/pywarpx/picmi.py#L1845
In principle, this should not require a lot of work, but at this point no one in our team is available to implement this (and do a clean PR with automated tests)