  The projector augmented wave (PAW) method of Bl\"ochl makes smooth but
non-orthogonal orbitals. Here we show how to make PAW orthogonal, using a cheap
transformation of the wave-functions. We show that the resulting Orthogonal PAW
(OPAW), applied for DFT, reproduces (for a large variety of solids) band gaps
from the ABINIT package. OPAW combines the underlying orthogonality of
norm-conserving potentials with the large grid spacings and small spectral
range in PAW. The OPAW framework can also be combined with other electronic
structure theory methods.
