  We modified a MPI-friendly density functional theory (DFT) source code within
hybrid parallelization including CUDA. Our objective is to find out how simple
conversions within the hybrid parallelization with mid-range GPUs affect DFT
code not originally suitable to CUDA. We settled several rules of hybrid
parallelization for numerical-atomic-orbital (NAO) DFT codes. The test was
performed on a magnetite material system with OpenMX code by utilizing a
hardware system containing 2 Xeon E5606 CPUs and 2 Quadro 4000 GPUs. 3-way
hybrid routines obtained a speedup of 7.55 while 2-way hybrid speedup by 10.94.
GPUs with CUDA complement the efficiency of OpenMP and compensate CPUs'
excessive competition within MPI.
