openMP+MPI occ-fft: 

make FFTDF faster for gamma and k-points PBC system by using occ- method 
It is just an uniform grids occ-sgX for PBC system by using FFT to get 1e integrals 

The openMP+MPI occ-fft is already in mpi4pyscf dev version, see the example 01-parallel_krhf_occ.py to do calculation.

Need PySCF