I'm testing some scaling properties of various density functional approximations, which involves evaluating the functionals on model systems with very low density. I am using the funcition
dft.libxc.eval_xc in PySCF, yet I found that when the density is lower than some specific thresholds, the function just returns zero instead of evaluating the functional.
I have read the PySCF python source code and found that this might be caused by the default density threshold of libxc, so I guess maybe I can disable that cut-off by modifying the file
pyscf/lib/libxc_itrf.so, but that seems kind of complicated for me. So I wonder if there is a more straightforward way to do such thing?
Thanks in advance for the help!