Efficient pseudopotentials for plane-wave calculations. II. Operators for fast iterative diagonalization

We present an investigation of the computational requirements for the pseudopotential plane-wave method as a function of the number of atoms per unit cell. For systems containing a large number of atoms the computational load can be reduced if the pseudopotential operator is of a suitable form, such that it can be efficiently calculated in the position representation. The pseudopotentials examined here include local pseudopotentials, position-dependent electron-mass pseudopotentials, and separable nonlocal pseudopotentials.