“…The iterative diagonalization of the Hamiltonian matrix is a computational bottleneck in real-space DFT calculations. To facilitate efficient diagonalization of the Hamiltonian, various iterative algorithms have been applied, − among which preconditioned iterative methods have been widely adopted in many real-space simulation codes. ,,,,, Despite recent advancements in iterative eigensolvers for real-space DFT, the overall efficiency is still hindered by the absence of efficient preconditioners.…”