Real-Space Orthogonal Projector-Augmented-Wave Method

The projector-augmented-wave (PAW) method of Blochl makes smooth but nonorthogonal orbitals. Here we show how to make a PAW orthogonal using a cheap transformation of the wave functions. We show that the resulting orthogonal PAW (OPAW), applied for density functional theory, reproduces (for a large variety of solids) band gaps from the ABINIT package. OPAW combines the underlying orthogonality of norm-conserving pseudopotentials with the large grid spacings and small energy cutoffs in PAW. The OPAW framework can also be combined with other electronic structure theory methods.